K-Epsilon Model

sangit

Hi,

I am a student of TU Munich Germany. And I am a novice in CFD. I am studying the k-epsilon turbulence model and using 2 equation of this model to simulate flow inside a pipe. I am discritisizing the two differential equations of k and epsilon and then having the values at new time step from that. But my problem is that at the wall I am using k=0 but there I donot know the value of epsilon .... i only know variation of epsion perpendicular to wall is zero. So I am putting the varitional derivative perpendicular to the wall is zero and calculating the value parallel to the wall from the epsilon discritisized equation .....

But My problem is that in the epsilon equation there is k in division which is eqaul to zero at wall .... and this is making my result to infinite ....and it is making the entire reults to infinte values ....because the two equations are coupled by k and epsilon of previous step ..... under the circumtances what should I do in the epsilon eqation at the wall .....

And also I have used the turbulent viscosity equal to zero where k is zero(though epsilon may be zero) .... is it correct .....

Any suggesion will be of great help to me .... as I am really confused