# LES initialization

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 September 13, 2008, 12:59 LES initialization #1 Abdel Dehbi Guest   Posts: n/a Sponsored Links Hello all, I want to use LES for turbulent pipe flow. After initialization of the RANS field following Fluent guidelines, I switch to LES, but I always end up with laminar flow. Any clue how I could initialize the flow to reach turbulent conditions with LES? Thanks. Abdel

 September 19, 2008, 07:54 Re: LES initialization #2 Paolo Lampitella Guest   Posts: n/a I'm simulating the turbulent channel flow and i used the logistic map: /************************************************** ******************** UDF for initialize the field with the logistic map ************************************************** ********************/ #include "udf.h" DEFINE_INIT(init_func,d) { cell_t c; Thread *t; real x[ND_ND]; real x0, y0, z0; real pi, ck, cn; real ax, ay, a0, ak; pi = M_PI; ck = 0.5; cn = 3.891; ax = 20.0*pi; ay = 20.0*pi; ak = ck; thread_loop_c(t,d) { begin_c_loop_all(c,t) { C_CENTROID(x,c,t); x0 = x[0]; y0 = x[1]; z0 = x[2]; a0 = ak; ak = cn*a0*(1-a0); C_U(c,t) = -20.0*y0*(y0-2) + 4.0*(0.5-ak); a0 = ak; ak = cn*a0*(1-a0); C_V(c,t) = 4.0*(0.5-ak); a0 = ak; ak = cn*a0*(1-a0); C_W(c,t) = 4.0*(0.5-ak); } end_c_loop_all(c,t) } } and it seems to work properly. Some stuff in the UDF is not used but it should work

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