5 Two Advanced Methods

The both advanced methods considering in this chapter are developed and intensively used during the last fifty years. The two phenomena—the turbulent flow and flow in flexible channels underlying the physical grounds of those methods—came from nature. The first one is most often flow regime in different occurrences in the world, and the second is the basic mechanism of human and primate organs transporting physiological fluids such as blood or urine. Due to that, the development of both methods was practically important, especially in a view of the possible wide applications. However, in the 1960s of the last century when the advent of the computer made possible the development of new methods, the initial scientific situation in two considered areas was completely different. At that time, the status of turbulence theory was close to the contemporary situation consisting of the Reynolds average equations (RANS) and even k − ϵ and k − ω turbulence models (S. 8.4.3). In contrast to that, the knowledge of flows in flexible channels of human organs at the same time correspond to the situation in biology that in the middle of the last century was basically a descriptive science consisting only verbal and illustrative information. This decisive distinction in starting conditions gives an understanding why the considered below new methods in turbulence are the top of the contemporary resources, whereas the modern means and results in the other topic studied here, the peristaltic motion in human organs, are only at the beginning level of present-day possibilities.