Wall Function Boundary Conditions Including Heat Transfer and Compressibility for Transport Turbulence Models

2004 ◽  
Author(s):  
Robert Nichols ◽  
Christopher Nelson
Keyword(s):  
Heat Transfer ◽  
Boundary Conditions ◽  
Turbulence Models ◽  
Wall Function

Wall Function Boundary Conditions Including Heat Transfer and Compressibility

AIAA Journal ◽  
2004 ◽  
Vol 42 (6) ◽  
pp. 1107-1114 ◽  
Author(s):  
R. H. Nichols ◽  
C. C. Nelson
Keyword(s):  
Heat Transfer ◽  
Boundary Conditions ◽  
Wall Function

Rough Surface Wall Function Treatment With Single Equation Turbulence Models

2017 ◽  
Vol 139 (8) ◽  
Author(s):  
U. Goldberg ◽  
P. Batten
Keyword(s):  
Heat Transfer ◽  
Kinetic Energy ◽  
Distance Function ◽  
Eddy Viscosity ◽  
Rough Surfaces ◽  
Turbulence Models ◽  
Single Equation ◽  
Current Approach ◽  
Wall Function ◽  
Wall Distance

Most literature in the area of turbulent flow over rough surfaces discusses methods for turbulence models based on two or more transport equations, one of which is that for turbulence kinetic energy which supplies k that is heavily used for the rough wall treatment. However, many aeronautical engineers routinely use single equation turbulence models which solve directly for eddy viscosity and do not involve k. The present work proposes methods by which such one-equation models can predict flow cases which include multiple rough surfaces. The current approach does not impose changes to the wall distance function, should such a function be necessary. Several examples show that the proposed method is able to produce good predictions of both skin friction and heat transfer along rough surfaces. While results are not always as accurate as those predicted by turbulence models which solve for k, especially if detached or wake-like flow regions exist, accompanied by a significant increase in eddy viscosity, the single-equation models are able to provide predictions at least good enough for preliminary studies.

A numerical investigation of heat transfer in a smooth bend part of a U-duct

2013 ◽  
Vol 24 (1) ◽  
pp. 137-147 ◽  
Author(s):  
Tareq Salameh ◽  
Bengt Sunden
Keyword(s):  
Heat Transfer ◽  
Boundary Conditions ◽  
Turbine Blades ◽  
Turbulence Models ◽  
Numerical Results ◽  
Temperature Fields ◽  
Heat Transfer Analysis ◽  
Content Type ◽  
Thermal Boundary Conditions ◽  
Wall Boundary Conditions

Purpose – The aim of this paper is to study two-dimensional numerical simulations of the flow and temperature fields inside the bend (turn) part of a U-duct. Design/methodology/approach – Several turbulence models based on two and five equations were used to solve the momentum and energy equations inside the bend (turn) part of the U-duct. For two-equation models, both the renormalization group and realizable k-ɛ turbulence models were implemented. The five-equation model used is a Reynolds stress model with different wall boundary conditions. Standard, non-equilibrium and enhanced wall functions were used in parallel with the two- and five-equation models to treat the turbulent flow near the duct walls. Findings – Several turbulence models were used to simulate the flow and temperature fields along the bend part of a U-duct with different inlet and thermal boundary conditions. The numerical results indicate that the renormalization and realizable k-ɛ turbulence models with standard wall function treatment gave the best results when compared with experimental data obtained for similar conditions. Research limitations/implications – For heat transfer analysis, two different thermal boundary conditions, i.e. constant wall temperature and constant heat flux at the wall are implemented. The results are calculated for Reynolds number equal 20,000. Practical implications – The results can be used in designing heat exchangers, piping and duct systems, and internal passage cooling of gas turbine blades. Originality/value – The numerical results obtained here concentrate on the detailed investigation of flow and temperature field at the outer wall of the bend part. Different boundary conditions at the inlet and the outer bend walls of the U-duct were applied to study how these boundary conditions affect the flow and temperature fields.

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