I am a new beginner working with k-e equations for turbulent flows. I am using low-reynolds version k-e equations with simple eddy viscosity method.
I have got a converged solution. But I found that the value of the dispation rate (e) is three order magnitude higher than the value of turbulent kinatic energy (k) generally. Is this reasonable result? I have no idea of this.
In general, is there any relationship between these two values?
I would be very grateful if any experienced one can tell me this. It is really hard to find such informaiton in the text book.
Thank you very much.
Re: k-e values
for y+ (y+ = y*u_f/nu) in [30:300], you can make the assumption that :
k = (u_f)^2/sqrt(c_\nu)
eps = (u_f)^3/(Kappa*y)
so k/eps which has to do whith the characteristic turbulent time scale is propto (Kappa*y)/(sqrt(c_nu)*uf)
which could be very small.
hope that help,
PS : Kappa = 0.41 ; c_nu = 0.09 ; nu = 1.5e-5 for air in mks ; u_f is the skin friction velocity.
|All times are GMT -4. The time now is 11:31.|