arXiv subjects

S. V. Utyuzhnikov

Publications and source records attributed to S. V. Utyuzhnikov.

3 recordsLinked to original sources

arXiv2005

Numerical Implementation of Generalized Robin-type Wall Functions and Their Application to Impinging Flows

The paper is devoted to the generalized wall functions of Robin-type and their application to near-wall turbulent flows. The wall functions are based on the transfer of a boundary condition from a wall to some intermediate boundary near the wall. The boundary conditions on the intermediate boundary are of Robin-type and represented in a differential form. The wall functions are formulated in an analytical easy-to-implement form, can take into account the source terms of the momentum equation, and do not include free parameters. The log-profile assumption is not used in this approach. A robust numerical algorithm is proposed for implementation of Robin-type wall functions to both finite-difference and finite-volume numerical schemes. The algorithm of implementation of the Robin-type wall functions to existing finite-volume codes is provided. The axisymmetric impinging jet problem is numerically investigated for different regimes on the base of the wall-functions implemented to the high-Reynolds-number k-epsilon model.

physics.comp-ph↗

arXiv2005

A Method for Generating a Well-Distributed Pareto Set in Nonlinear Multiobjective Optimization

In multidisciplinary optimization the designer needs to find solution to optimization problems which include a number of usually contradicting criteria. Such a problem is mathematically related to the field of nonlinear vector optimization where there are many numerical methods capable of providing a solution. However, only a few of those are suitable for real multidisciplinary design in industry because an iteration design circle usually is very time-consuming. This is due to the time scales and computational resources associated with each iterative design cycle. The recently suggested Physical Programming Method appears to match many requirements raised in industrial applications. The method is modified to make its realization easier and more efficient, the main focus being the even generation of the complete Pareto set. The method is used to find the Pareto surface for different test cases.

math.OC↗

arXiv2003

On some numerical methods in application to low-Reynolds-number turbulence models

To study and develop wall-functions for low-Reynolds-number models, a model linear equation is introduced. This equation simulates major mathematical peculiarities of the low-Reynolds-number model including a near wall sub-layer and transition region. Dirichlet and Newman boundary-value problems are considered. The standard and analytical wall-functions are investigated on different properties including the mesh sensitivity of a solution. A Robin-type interpretation of wall functions as boundary conditions is suggested. It is shown that solution of a problem is mesh independent and more accurate in this case. General type analytical and numerical wall-functions are developed on the basis of a boundary condition transfer. An effective numerical method of decomposition is suggested. The method can be used in application to either high-Reynolds-number models with the numerical wall-functions or low-Reynolds-number models directly. Although a model equation is considered, the formulas, methods and conclusions are valid and can be directly used for real low-Reynolds-number equations.

physics.comp-ph↗