LES In Turbulent in channel flow

pankaj saha

Hi,

I am solving Turbulent channel flow by LES. But, i am facing problem as follows.---

I am not using any software. i am using my own code in fortran language.

For the channel----

i am taking periodic b.c in streamwise and spanwise direction.

dimension--4pi*2*2pi and grid 50*56*66

Re=205, corresponding friction velocity and half channel height.

So, i am using mean driving pressure gradient=1.0

for initial condition: u(x,y,z)=(1-y**8)+0.005*(rand(iseed)-0.5). /////Rand gives value , between 0,1, y is wall normal coordinate.

also, v(x,y,z)=0.0

w(x,y,z)=0.0

using---2nd order cd for convective and diffusive discretization. and adam-bashforth for time .

time step--0.0002

The problem is , i saw the mean velocity increase and reaches a very high value during the simulation.

also, along the channel centerline, i check the instantaneous u, v, w velocity----it does not show any turbulence.

what is the remedy....can anybody share his experience , during channel flow simulation.

thanks in advance.