CFD Online Discussion Forums (https://www.cfd-online.com/Forums/)
-   Main CFD Forum (https://www.cfd-online.com/Forums/main/)
-   -   Initial conditionfor turbulent channel flow in LES (https://www.cfd-online.com/Forums/main/14454-initial-conditionfor-turbulent-channel-flow-les.html)

 pankaj saha November 30, 2007 13:04

Initial conditionfor turbulent channel flow in LES

hi, i am solving fully developed plane channel flow by LES. I am using periodic boundary condition in steramwise(x-direction),and spanwise(z-direction).A no slip b.c for top and bottom wall(y-direction).

For initial condition i am taking a fully developed mean profile with random perturbation for the u-component (streamwise)of velocity. and v=0,w=0. like as follows...

For the whole domain---- u(x,y,z)=(1-y**8)+0.005*(RAND(x,y,z)-0.5 v(x,y,z)=0.0 w(x,y,z)=0.0

And in fortran programming language---

IND=0

do 55 i=1,iim

do 55 j=1,jim

do 55 k=1,kim

u(i,j,k)=(1-y(j)**8)+0.005*(RAND(IND)-0.5)

v(i,j,k)=0.0

w(i,j,k)=0.0

p(i,j,k)=1.0

IND=IND+1

55 continue

i,j,k--is spatial grid in three directions

iim=maximum grid no in x-direction

jim=maximum grid no in y-direction

kim=maximum grid no in z-direction

RAND(IND)------is a inbuilt function in fortran. As, the value of IND , change in the loop--then RAND(IND), will give a value , between--0.0-1.0

my question is---------

1. Is my approach correct.

2.Do i need random values for v and w velocity component.

3.Do i need to change the random function.