DNS 1-2 Description: Difference between revisions
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computational setup to make the computations feasible and avoid uncertainty or ambiguity. | computational setup to make the computations feasible and avoid uncertainty or ambiguity. | ||
= Description of the test case = | = Description of the test case = | ||
An idealised channel flow, without side walls, is considered. The details of the case are given in [https://www.cambridge.org/core/journals/journal-of-fluid-mechanics/article/identifying-eigenmodes-of-averaged-smallamplitude-perturbations-to-turbulent-channel-flow/EF03E2FFFF1A481FC55448B3F11496F2 Iyer et al.(2019)]. The current set of simulations has a higher grid resolution in the wall normal direction. | |||
==Geometry and flow parameters== | ==Geometry and flow parameters== | ||
The geometry is a cuboid of dimensions <math>8\pi</math> units in the streamwise direction <math>(x)</math>, 2 units in the transverse direction <math>(y)</math> and <math>4\pi</math> units in the spanwise direction <math>(z)</math>. The dimensions are normalised by the channel half-width, <math>h</math> and centreline velocity. The Taylor Reynolds number is 180. | |||
The geometry is a cuboid of dimensions 8 | |||
<!-- Describe the general set up of the test case and provide a sketch of the geometry, clearly identifying location and type of boundaries. Specify the non-dimensional flow parameters which define the flow regime (e.g. Reynolds number, Rayleigh number, angle of incidence etc), including the scales on which they are based. Provide a detailed geometrical description, by preference in form of a CAD, or alternatively as lists of points and a description of the interpolation. --> | <!-- Describe the general set up of the test case and provide a sketch of the geometry, clearly identifying location and type of boundaries. Specify the non-dimensional flow parameters which define the flow regime (e.g. Reynolds number, Rayleigh number, angle of incidence etc), including the scales on which they are based. Provide a detailed geometrical description, by preference in form of a CAD, or alternatively as lists of points and a description of the interpolation. --> | ||
==Boundary conditions== | ==Boundary conditions== | ||
The domain is periodic in the streamwise and spanwise directions which gives a flow developing in time. The transverse boundaries are viscous walls with no-slip boundary conditions. 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. | |||
The domain is periodic in the streamwise and spanwise directions which gives a flow developing in time. The transverse boundaries are viscous walls with no-slip boundary conditions. The initial density and pressure fields are uniform. The initial velocity field is | |||
<!-- 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 06:30, 6 October 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
Provide a brief review of related past studies, either experimental or computational. Identify the configuration chosen for the present study and position it with respect to previous studies. If the test case is geared on a certain experiment, explain what simplifications ( e.g. concern- ing geometry, boundary conditions) have been introduced with respect to the experiment in the computational setup to make the computations feasible and avoid uncertainty or ambiguity.
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). 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. The Taylor Reynolds number is 180.
Boundary conditions
The domain is periodic in the streamwise and spanwise directions which gives a flow developing in time. The transverse boundaries are viscous walls with no-slip boundary conditions. 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.
Contributed by: Arun Soman Pillai, Lionel Agostini — Imperial College London
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