DNS 1-2 Description: Difference between revisions
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Periodicity conditions are imposed in the streamwise and spanwise boundaries which gives a flow developing in time. The transverse boundaries are no-slip walls. The initial density and pressure fields are uniform. The initial velocity field is <math>(u,v,w)=\left(1-y^2/h^2,0,0\right)</math>. The solution is started at order 2 and progressively increased to order 5. | |||
<!-- Specify the prescribed boundary conditions, as well as the means to verify the initial flow development. In particular describe the procedure for determining the in flow conditions comprising the instantaneous (mean and fluctuating) velocity components and other quantities. Provide reference profiles for the mean flow and fluctuations at in flow - these quantities must be supplied separately as part of the statistical data as they are essential as input for turbulence-model calculations. For checking purposes, these profiles should ideally also be given downstream where transients have disappeared; the location and nature of these cuts should be specified, as well as the reference result. --> | <!-- Specify the prescribed boundary conditions, as well as the means to verify the initial flow development. In particular describe the procedure for determining the in flow conditions comprising the instantaneous (mean and fluctuating) velocity components and other quantities. Provide reference profiles for the mean flow and fluctuations at in flow - these quantities must be supplied separately as part of the statistical data as they are essential as input for turbulence-model calculations. For checking purposes, these profiles should ideally also be given downstream where transients have disappeared; the location and nature of these cuts should be specified, as well as the reference result. --> | ||
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Revision as of 10:30, 7 December 2021
Introduction
The turbulent Channel Flow is one of the canonical flows used to study turbulence in wall bounded turbulence. DNS of turbulent channel flow were undertaken at . DNS were undertaken using PyFR (http://www.pyfr.org/) version 1.12.0:
- based on the high-order flux reconstruction method of Huynh
- compressible solver
- a Rusanov Riemann solver was employed to calculate the inter-element fluxes
- an explicit RK45[2R+] scheme was used to advance the solution in time
- Fifth order polynomials are used for the computations
Review of previous studies
Turbulent channel has been one of the canonical test cases to study the characteristics of wall bounded turbulence. The simplified setup proposed by Kim et al. (1987)[1] is now a standard test case for wall bounded turbulent flow simulations. The setup is computationally inexpensive as it a periodic channel flow with periodic boundary conditions in the spanwise and streamwise directions. With recent progress made in computing infrastructure, Reynolds numbers as large as (Bernardini et al. 2014) and (Pirrozoli et al. 2021) are now available. Nevertheless, the case by Kim et al. still remains as a benchmark case for wall bounded turbulent flow simulations.
Description of the test case
An idealised channel flow, without side walls, is considered. The details of the case are given in Iyer et al.(2019)[2]. The current set of simulations has a higher grid resolution in the wall normal direction.
Geometry and flow parameters
The geometry is a cuboid of dimensions units in the streamwise direction , 2 units in the transverse direction and units in the spanwise direction . The dimensions are normalised by the channel half-width, and centreline velocity.
Boundary conditions
Periodicity conditions are imposed in the streamwise and spanwise boundaries which gives a flow developing in time. The transverse boundaries are no-slip walls. The initial density and pressure fields are uniform. The initial velocity field is . The solution is started at order 2 and progressively increased to order 5.
References
- ↑ Kim,J., Moin, P. and Moser, R., Turbulence statistics in fully developed channel flow at low Reynolds number, J. Fluid Mech. 177, 133-166, 1987
- ↑ A. Iyer, F. D. Witherden, S. I. Chernyshenko and P. E. Vincent, Identifying eigenmodes of averaged small-amplitude perturbations to turbulent channel flow, Journal of Fluid Mechanics, 875 (758-780), 2019
Contributed by: Arun Soman Pillai, Lionel Agostini — Imperial College London
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