The failure of engines on jet aircrafts during the past few years has prompted the National Transportation Safety Board (NTSB) to issue an “urgent” recommendation to increase inspections of the engines on U.S. aircraft. Such uncontained engine failures are particularly dangerous, because flying engine parts could puncture fuel or hydraulic lines, damage flight surfaces or even penetrate the fuselage and injure passengers. At issue is older engines found on small number of jets, and the safety and economic impact damage and fracture risk can have on aircraft engines. For example, high-pressure turbine blades are commonly removed from commercial aircraft engines that had been commercially flown by airlines. These engines were brought to the maintenance shop for refurbishment or overhaul. The blades were removed and inspected for damage. The damage was cataloged into three modes of failure, which are thermal-mechanical fatigue (TMF), Oxidation/Erosion (O/E), and Other (O). These show the complexity of damage in turbine engines and the different mechanisms associated with cause of damage. Hence, life prediction of turbine engine is crucial part of the management and sustainment plan to aircraft jet engine. Fretting is often the root cause of nucleation of cracks at attachment of structural components at or in the vicinity of the contact surfaces. Previous effort presented a model to predict fretting fatigue in turbine engine, which is one of the primary phenomena that leads to damage or failure of blade-disk attachments. The influence of thermal effect and temperature fluctuation during engine operation on fretting fatigue damage were investigated. Leveraging these existing capabilities, the present effort focuses on modeling another important damage mechanism in turbine engine blades, which is erosion at high temperatures. Thus a reaction-diffusion model is implemented in addition to the thermo-mechanical one. The model provides a mean to investigate erosion initiation and propagation in turbine engine blades.

A thermodynamically consistent constitutive model of metallic glass is presented by extending the infinitesimal deformation model of Huang et al. [Huang, R., Suo, Z., Prevost, J. H., and Nix,W. D., 2002.Inhomogeneous deformation in metallic glasses,J. Mech. Phys. Solids, 40, 1011–1027] to finite deformation. The underlying theory behind the model is the free volume theory with free volume concentration as the order parameter affected through the processes of diffusion, annihilation and creation. The main assumptions of the model include multiplicative decomposition of deformation gradient and additive decomposition of free energy. The former comprises of elastic, inelastic dilatational component associated with excess free volume concentration and isochoric plastic part while the latter consists of contributions from elastic deformation and free volume concentration. The plastic part evolves according to Mises-theory and the local free volume concentration. Homogeneous simple shear is the model problem solved using the present model and compared with the infinitesimal deformation theory to examine the effect of large deformation on stresses in metallic glasses.

This study investigates the effect of membrane properties — porosity, membrane thickness, and pore radius — on the performance of vacuum membrane distillation (VMD) process by achieving computational fluid dynamics (CFD) simulations on a three-dimensional domain of interest at fixed flow properties. The finite volume method (FVM) is adopted to solve momentum, solute mass transport, and energy equations in the feed channel. To accurately predict the rate of water vapor diffused through the membrane by Knudsen and viscous diffusion mechanism, local concentration, temperature, and flux are coupled at the membrane surfaces. In accordance with the flux, corresponding gradients for temperature and concentration are applied at the membrane boundaries. Since there is a strong coupling of flow properties at the membrane surface, the employed model is validated against an experimental study and further used to characterize the effect of PTFE membrane properties on permeate flux, temperature polarization, and concentration polarization. We found that different set of membrane design parameters substantially changes the total mass flux. The contribution of both viscous and Knudsen mechanism is comparable and, as such, prevents us neglecting neither of them. The temperature and concentration polarization are even more undesirable level for the larger pore sizes.

This work investigates the effect of negative dielectrophoresis (DEP) on polystyrene particles inside an evaporating DI water droplet on a PDMS surface. Deposition patterns of actuated droplets transitioned from a scalloped rings to a striped deposition pattern as the particle diameter increased from 20 nm to 1 μm. Increased particle size dramatically increases the negative DEP force on particles that push them toward the lower field gradient expected in fluid between active electrodes. Interestingly, deposition patterns became more uniform when particle diameter was increased to 5 μm. This uniform pattern appears to be due to interfacial trapping as the diffusion rate of the large particles was significantly slower than the velocity of the descending interface. This work suggests that DEP can be used to control deposition patterns left by evaporating colloidal droplets, but further work examining the electric field gradient inside the droplet is required to determine if this technique can be applied to a wider range of particle sizes.

Mild traumatic brain injury (TBI) is a very common injury to service members in recent conflicts. Computational models can offer insights in understanding the underlying mechanism of brain injury, which can aid in the development of effective personal protective equipment. This paper attempts to correlate simulation results with clinical data from advanced techniques such as magnetic resonance imaging (MRI), diffusion tensor imaging (DTI), functional MRI (fMRI), MR spectroscopy and susceptibility weighted imaging (SWI), to identify TBI related subtle alterations in brain morphology, function and metabolism. High-resolution image data were obtained from the MRI scan of a young adult male, from a concussive head injury caused by a road traffic accident. The falling accident of human was modeled by combing high-resolution human head model with an articulated human body model. This mixed, multi-fidelity computational modeling approach can efficiently investigate such accident-related TBI. A high-fidelity computational head model was used to accurately reproduce the complex structures of the head. For most soft materials, the hyper-viscoelastic model was used to captures the strain rate dependence and finite strain nonlinearity. Stiffer materials, such as bony structure were simulated using an elasto-plastic material model to capture the permanent deformation. We used the enhanced linear tetrahedral elements to remove the parasitic locking problem in modeling such incompressible biological tissues. The bio-fidelity of human head model was validated from human cadaver tests. The accidental fall was reconstructed using such multi-fidelity models. The localized large deformation in the head was simulated and compared with the MRI images. The shear stress and shear strain were used to correlate with the post-accident medical images with respect to the injury location and severity in the brain. The correspondence between model results and MRI findings further validates the human head models and enhances our understanding of the mechanism, extent and impact of TBI.

The twentieth century has seen a rapid twenty-fold increase in the use of fossil fuels. Personal and commercial transportation consumes 2% of the total world energy. The main products of combustion of fossil fuel are carbon mono oxide (CO), unburned hydrocarbons (HC), Carbon dioxide (CO 2 ), oxides of sulfur (SO x ), oxides of nitrogen (NO x ) and particulate matter. Oxides of nitrogen (NO x ) are the major diesel engine pollutants and referred to as mixtures of nitric oxide (NO) and nitrogen dioxide (NO 2 ). NO x emissions are required to be controlled because NO and NO 2 contribute to the formation of smog, an environmental and human health hazard. NO 2 is also directly of concern as a human lung aggravation. To reduce NO x emissions from a diesel engine, the introduction of water in the combustion chamber of a diesel engine is a promising option as vaporization of water reduces adiabatic flame temperature and micro-explosion phenomena lead to improved mixing. In the present study, stable D/W emulsion, with varying water content, up to 3% were prepared using span 80 as a surfactant. The results indicated a reduction in NO x and smoke with increasing water volume fraction in the emulsion compared to diesel baseline. However, beyond 2% water content led to increased ignition delay and higher diffusion phase heat release resulting in noisy engine operation. Therefore, it can be concluded that diesel-water emulsion with 2% water could be used for significant reduction of NO x emissions from diesel and biodiesel operation of a CI Engine.

Enabling fast charging of Li-ion batteries (LiB) is essential for mainstream adoption of electric vehicles (EVs). A critical challenge to fast charging is lithium plating, which can lead to drastic capacity loss and safety risks. Fundamentally, fast charging is restricted by anode surface reaction kinetics, lithium diffusion in anode solid particles and Li + diffusion and conduction in electrolyte. In this work, we present an analysis of the contributions of these different physicochemical processes to the total overpotential during fast charging, using an electrochemical-thermal (ECT) coupled model. Special attention is paid to the effect of increasing electrode thickness, a common approach for raising energy density of EV cells, on fast charging capability. It is found that lithium plating is more prone to occur in thicker anodes due to larger electrolyte transport resistance. Furthermore, we present a novel approach of thermal stimulation to enable 10-minutes (6C rate) fast charging of an EV cell with 170Wh/kg energy density.

Nearly everyone, throughout their life, is at risk of being involved in a serious traumatic event, such as motor vehicle accidents, sports and occupational injuries, or natural disaster related injuries. Twenty-eight percent of trauma patients precipitously develop abnormalities in their blood coagulation system. These coagulopathies increase their mortality rate by 5fold. The current coagulopathy diagnosis protocol collects basic patient information, vital signs, and performs traditional lab and point-of-care (POC) blood testing. A high-stakes decision must then be made by the trauma surgeon, using their intuition, training, and the results from the blood drawn at least 15 minutes prior, to determine the requirement for a resuscitation treatment through coagulation inhibitors or activators. Computational modeling and system analysis of the human blood coagulation are integral to developing superior decision support tools for trauma surgeons. In short, the coagulation system consists of the following functional subsystems: 1) blood flow, 2) platelet function, 3) diffusion, 4) advection, and 5) biochemical kinetics. We utilize a combined approach of both 0-D and 3-D model development with the overarching goal of developing a validated, near real-time decision support system. The biochemical kinetics of the coagulation system is implemented in the 0-D model with a set of 113 nonlinear, coupled ordinary differential equations (ODEs), describing the time rate of change of the numerous chemical concentrations and their interaction with one another. 0-D models provide a fast, efficient means of simulating the coagulation biochemical kinetics, but these ODEs lack the ability to describe the global effects of fluid flow, advection, and diffusion. Hence, the set of 113 ODEs are modeled as source terms and combined with the Navier-Stokes and chemical advection/diffusion equations in a three-dimensional finite volume computational domain, providing a global coagulation model. Model validation studies employ parallel experimental POC blood testing and 3-D computational modeling. Results from the 0-D model are consistent with testimonials from expert trauma surgeons, whom verify the model provides appropriate reasoning for their difficulties in predicting patient outcome. Thus, validated computational models have potential as a hypothesis generator used for developing new approaches for providing trauma surgeons with sufficient information to make better informed clinical decisions, “the decision support tool,” leading to decreased mortality.

As research continues into the generation IV advanced nuclear reactors, exploration of liquid sodium as a coolant, or Sodium Fast Reactors (SFRs), coupled to supercritical CO2 (sCO2) Brayton cycles are currently underway. Liquid sodium offers unique and beneficial fluid properties that can achieve higher efficiencies and longer equipment lifespans compared to conventional water cooled reactors. Coupling sodium with sCO2 matches well with sodium’s temperature profile and is less reactive with sodium when compared to water used in standard Rankine cycles. To achieve commercial viability, methods for developing diffusion-bonded Hybrid Compact Heat Exchangers (H-CHX) to couple SFRs with sCO2 Brayton cycles are being developed. This paper includes thermal-hydraulic analysis of these fluids to quantify thermal and pressure stresses within the H-CHX for use in determining a structurally sound design. Two models for predicting the temperature profiles within a practical H-CHX channel design are presented. The first is a 1-D heat transfer model employing heat transfer correlations to provide both bulk fluid and wall temperatures. The second is a 3-D computational fluid dynamics model (CFD) providing a three-dimensional temperature profile, but at a significantly increased simulation time. By comparing the results of the two models for specific design conditions, significant temperature deviation is shown between the models at a short channel length of 10 cm. However, for longer channel lengths, although the 1-D model neglected the strong axial conduction on the sodium side, it generally shows good agreement with the CFD model. Thus, for any practical H-CHX designs, the findings reveal both simulation methods can be used to extrapolate the temperature gradient along the channel length for use in designing a H-CHX, as well as predicting the overall size and mass of the heat exchanger for component costing.

Modeling the heat transfer characteristics of the highly turbulent flow in gas turbine film cooling is important for better engineering solutions to the film cooling system design. URANS, LES, DES and modified DES models capability in simulating film cooling with a density ratio of 2.0 and blowing ratio of 1.0 are studied in this work. Detailed comparisons of simulation results with experimental data regarding the near-field and far-fields are made. For near field predictions, DES gives decent prediction with a 21.4 % deviation of centerline effectiveness, while LES and URANS have deviation of 33.6% and 51.2% compared to the experimental data. Despite good predictions for near field, DES under predicts the spanwise spreading of counter rotating vortex pair and temperature field, therefore it over predicts the centerline effectiveness in the far field. To compensate for this shortcoming of DES, the eddy viscosity in the spanwise direction is increased to enhance spanwise-diffusion of the cooling jets. The modified DES prediction of overall centerline effectiveness deviates 12.4% from experimental data, while LES, unmodified DES and URANS predictions deviate 10.8%, 31.9% and 46.9%. The modified DES model has adequate predictions of vortices evolutions which URANS modeling lacks and consumes significant less computational time than LES. It can be said that the modified DES model results in satisfactory film cooling modeling with a moderate computational cost and time.

Monolithic plate-type fuel is a fuel form that is being developed for the conversion of high performance research and test reactors to low-enrichment uranium fuels. These fuel-plates are comprised of a high density, low enrichment, U-Mo alloy based fuel foil encapsulated in an aluminum cladding. To benchmark this new design, number of plates has been irradiated with satisfactory performance. As a part of continuing evaluation efforts, a set of plates covering range of operational parameters is scheduled to be tested during MP-1 irradiation experiments. It is necessary to evaluate the thermo-mechanical performance of plates during irradiation. For this, selected plates with distinct operational histories; covering low power, high power and high fission density were simulated. Fully coupled three-dimensional models of plates with a capability to evolve mechanical and thermal properties of constituent materials with irradiation time and burn-up were developed. The models input used projected parameters, including plate geometry, irradiation history and coolant conditions as input. The model output included temperature, displacement and stresses in the fuel, cladding and diffusion barrier. The fuel behavioral model considered inelastic behavior including volumetric swelling due to solid and gaseous products, irradiation induced creep, thermal expansion, conductivity degradation and plasticity. A visco-plastic behavioral model was used for the cladding that included thermal creep, irradiation hardening, growth due to fast neutrons and Mises plasticity. The plates were then simulated by using projected irradiation parameters. The resulting temperature, displacement and stress-strains were comparatively evaluated on the selected paths. The results were then compared with those of plates from previous RERTR experiments.

Electroplated gold thin films have been used for micro bumps in flip chip packing structures. However, it has been reported that physical properties and micro texture of the electroplated thin films vary drastically comparing with those of conventional bulk material, depending on their electroplating process. In addition, since one bump is going to consist of a few grains or a single grain due to the miniaturization of the 3D structures, it shows strong anisotropic mechanical properties because a face-centered cubic crystal essentially has strong anisotropy of physical properties. Therefore, there should be the wide distribution of characteristics of the micro bumps depending on their micro structure and the variation of the crystallinity of grains and grain boundaries enlarges the width of the distributions of various properties. Particularly, it was found that the long-term reliability of micro bumps and interconnections is degraded drastically by porous grain boundaries with a lot of defects because of the acceleration of atomic diffusion along the porous grain boundaries under the application of high current density (electromigration) and high mechanical stress (stress-induced migration). In this study, the effect of crystallinity, in other words, the order of atom arrangement of grain boundaries in electroplated gold thin films on the EM resistance was investigated experimentally. The crystallinity of the gold thin films was varied drastically by changing the under-layer material used for electroplating; such as Cr (30 nm) / Pt (50 nm)/ Au (200 nm) and Ti (50 nm) / Au (100 nm). The mechanical properties of the electroplated gold thin films were measured by using a nano-indentation test. Also, the micro textures such as crystallinity and crystallographic orientation of gold thin films were investigated by EBSD (Electron Back-Scatter Diffraction) and XRD (X-Ray Diffraction). It was clarified that the crystallinity of the electroplated gold thin films changed drastically depending on the crystallinity of the under-layer materials and heat treatment conditions after electroplating. This variation of the crystallinity should have caused the wide variation of mechanical properties of the electroplated gold films. Therefore, it is very important to control the crystallinity of the under layer used for electroplating in order to control the mechanical properties and reliability of the electroplated gold thin films.

The change of the lath martensitic structure in the modified 9Cr-1Mo steel was observed in the specimens after the intermittent fatigue and creep tests using EBSD (Electron Back-Scatter Diffraction) analysis. The Kernel Average Misorientation (KAM) value and the image quality (IQ) value obtained from the EBSD analysis were used for the quantitative evaluation of the change in the lath martensitic texture. It was found that the lath martensitic texture started to disappear clearly after 10 7 –10 8 cycles under the fatigue loading at temperatures higher than 500°C when the amplitude of the applied stress exceeded a critical value. Similar change also appeared in the creep test. The critical value decreased monotonically with the increase of the test temperature. This microstructure change decreased the strength of the alloy drastically. In order to explicate the dominant factors of the change quantitatively, the changes of the microstructure and the strength of the alloy were continuously measured by applying an intermittent creep test at elevated temperatures. It was found that the effective activation energy of atomic diffusion decreased drastically under the application of mechanical stress at elevated temperatures. The effective diffusion length for the disappearance was about 9 μm, and this value was much larger than the initial pitch of the lath martensitic texture of about 0.5 μm, and smaller than the average size of the initial austenite grains of about 20 μm. Therefore, the stress-induced acceleration of atomic diffusion was attributed to the disappearance of the initially strengthened micro texture. The change of the micro texture caused the drastic decrease in the yielding strength of this alloy. Finally, the prediction equation of the lifetime of the alloy was proposed by considering the stress-induced acceleration of atomic diffusion under the application of mechanical stress at elevated temperatures.

In this paper, the analytical solutions of periodic evolution of Brusselator are investigated through the general harmonic balanced method. Both stable and unstable, period-1 and period-2 solutions of the Brussellator are presented. Stability and bifurcations of the periodic evolution are determined by the eigenvalue analysis. Numerical simulations of stable period-1 and period-2 motions of Brusselator are completed. The harmonic amplitude spectrums show harmonic effects on periodic motions, and the corresponding accuracy of approximate analytical solutions can be prescribed specifically.

Improvement in power generation performance of PEFC (Polymer Electrolyte Fuel Cell) is required for its market supremacy in automotive applications. In particular, it is important to suppress concentration overpotential in high current density operation. The microstructure of CCL (cathode catalyst layer) is known to have a great effect on the power generation performance of PEFC. Also, the requirement for the species transport characteristics should vary with the thickness-wise position in CCL. Therefore, the purpose of this study is to design the microstructure of CCL by using multi-layered cathode catalyst layer and to evaluate oxygen transport properties. In this research, we fabricated three kinds of multi-layered CCLs which have the difference in I/C (ionomer to carbon) ratio of GDL (gas diffusion layer)-side layer (0.3, 0.5, 0.9). And, we investigated oxygen transport-reaction phenomena by evaluating polarization characteristics, ECA (electrochemical surface area) and R CL (oxygen transport resistance in the CCL) using limiting current measurements. As I/C ratio is decreased from 0.9 to 0.5, R CL is decreased 49%. On the contrary, as I/C ratio is decreased from 0.5 to 0.3, R CL is slightly increased. ECA is monotonically decreased as I/C ratio is decreased from 0.9 to 0.3. These results show that the species transport characteristics alone have optimum condition in the GDL-side CCL at around I/C = 0.50. In addition, we fabricated four kinds of multi-layered CCLs which have the difference in I/C ratio of GDL-side layer (0.5, 0.9) and mass fraction of platinum (10 wt%, 46 wt%.) Oxygen transport resistance is evaluated in CCL by separating the resistance to two components, R macro (by Knudsen diffusion) and R local (by dissolution diffusion in ionomer,) by applying the ladder resistance model in CCL. As I/C ratio is decreased from 0.9 to 0.5, R macro is decreased and R local is increased regardless of mass fraction of Pt. These results show that the ionomer amount of micropore in CCL is decreased, the micropore diameter is increased, and dissolution surface area near platinum is decreased as I/C ratio is decreased 0.9 to 0.5. These results strongly suggest that there is an optimization strategy of I/C ratio of GDL-side layer in CCL.

In the field of additive manufacturing process, laser cladding is widely considered due to its cost effectiveness, small localized heat generation and full fusion to metals. Introducing nanoparticles with cladding metals produces metal matrix nanocomposites which in turn improves the material characteristics of the clad layer. The strength of the laser cladded reinforced metal matrix composite are dependent on the location and concentration of the nanoparticles infused in metals. The governing equations that control the fluid flow are standard incompressible Navier-Stokes and heat diffusion equation whereas the Euler-Lagrange approach has been considered for particle tracking. The mathematical formulation for solidification is adopted based on enthalpy porosity method. Liquid titanium has been considered as the initial condition where particle distribution has been assumed uniform throughout the geometry. During the solidification process of liquid titanium, particle flow and distribution has been observed until the entire geometry solidified. A numerical model implemented in a commercial software based on control volume method has been developed that allows to simulate the fluid flow during solidification as well as tracking nanoparticles during this process. The influence of the free surface of the melt pool has a high importance on the fluid flow as well as the influence of pure natural convection. Thus both buoyancy and Marangoni convection have been considered in terms of fluid flow in the molten region. A detailed parametric study has been conducted by changing the Marangoni number, convection heat transfer coefficient, constant temperature below the melting point of titanium and insulated boundary conditions to analyze the behavior of the nanoparticle movement. With the change in Marangoni number and solidification time, a significant change in particle distribution has been observed. The influence of increase in Marangoni number results in a higher concentration of nanoparticles in some portions of the geometry and lack of nanoparticles in rest of the geometry. The high concentration of nanoparticles decrease with a decrease in Marangoni number. Furthermore, an increase in the rate of solidification time limits the nanoparticle movement from its original position which results in different distribution patterns with respect to the solidification time.

A numerical solution based on a varying node volume for the mass diffusion, thermal response during a dilution experiment of a reacting mixture was performed. The unique feature of the solution was its use of partial volumes and incorporating the changes in heat transfer area and internal node volume changes. The limiting behavior of these transient responses was in agreement with expected analytical results. The resulting temperature and concentration responses were used with a typical EOT calibration relation to estimate its response during an experiment. The calculated EOT and temperature time response exhibit the same trends as that observed experimentally.

Compressed earth blocks constructions are appropriate for the improvement of the housing conditions in poor contexts, in particular in developing countries. The blocks are produced using manually operated presses, preferably bidirectional. The bidirectional human powered presses currently available are mechanically complex, difficult to use and very expensive. In order to overcome these issues, the paper presents the concept and the design of a new bidirectional human powered press for compressed earth blocks, called Float-Ram. The press is characterized by: the adoption of a floating mold, which provides a bi-directional pressing action in simple way; an optimized kinematic structure, based on a cam-roller follower transmission system; a general mechanical simplicity, since the node of all kinematic pairs is constituted by a single shaft. The Float-Ram, tested on the laboratory and on the field, can be considered as an important media for the diffusion of high-quality raw earth building in developing countries.

Reverse Osmosis (RO) is a process whereby solutes are removed from a solution by means of a semipermeable membrane. Providing access to clean water is one of our generation’s grand engineering challenges, and RO processes are taking center stage in the global implementation of water purification technologies. In this work, computational fluid dynamics simulations are performed to elucidate the steady state phenomena associated with the mass transport of solution through cylindrical hollow fiber membranes in hopes of optimizing RO technologies. The Navier-Stokes and mass transport equations are solved numerically to determine the flow field and solute concentration distribution in the hollow fiber membrane bank, which is a portion of the three-dimensional feed channel containing a small collection of fibers. The k-ω Shear Stress Transport turbulence model is employed to characterize the flow field. Special attention is given to the prediction of water passage through hollow fiber membranes by the use of the solution-diffusion model, which couples the salt gradient, water flux, and local pressure at the membrane surface. This work probes hollow fiber membrane arrangement in the feed channel by considering inline and staggered alignments. Feed flow rates for Reynolds number values ranging between 400 and 1000 are considered. Increased momentum mixing within the feed channel solution can substantially enhance the system efficiency, and hollow fiber membrane arrangements and feed flow rates dictate the momentum mixing intensity. Velocity and vorticity iso-surfaces of the flow domain are presented in order to assess the momentum mixing achieved with various hollow fiber membrane arrangements and flow rates. The total water permeation rate per hour is calculated to compare system efficiencies, and the coefficient of performance is calculated to compare membrane performance relative to the necessary power input, both for the various hollow fiber membrane arrangements and feed flow rates.

The diffusion of radioactive material in the atmosphere is vital for environmental assessment. Many researches have focused on the diffusion and deposition outside the construction, whereas less attention was paid on the law of the diffusion from the outside into the room. In this paper, three-dimensional numerical simulation was carried out by using OpenFOAM, an open source software for CFD. The incompressible steady flow around the construction with opening windows was investigated. The influence of inflow wind velocity and windows distribution was considered. The results show that as the inflow wind velocity increases, the diffusion is more significant. The vortexes is related to the windows distribution. When windows are perpendicular to the direction of the inflow wind, the concentration inside the construction is higher than that outside. Besides, the radioactive material gathers in the vicinity of the indoor downstream wall. When windows are parallel to the direction of the inflow wind, the concentration of indoors and outdoors is opposite, and the indoor radioactive material is distributed evenly. This study can provide theoretical support for the emergency evacuation around the construction.