k-epsilon model with LBM
 

Hi For my thesis I am implementing k-epsilon model for backward step. So for that reason I am using the the standard Launder and Spalding model with wall function. And I am assigning the boundary values at the first nodes from the wall for k and epsilon. Also I am initializing the initial value of k and epsilon at inlet.The equation of the boundary values are at 1st nodes from wall : k=utau^^2*sqrt(c_mu) and epsilon=utau^^3/(kappa*delta) . How can i calculate the utau and y+ at the first node. I know that the initial values are valid if y is between 20 to 100 .And what will be the value of delta as it is the distance from the wall to the 1st node ... in my velocity mesh it is y=1 .... So i am confused .... how can I proceed .... any step by step calculation for utau , y+ and delta will be very much helpful ......