# PARABOLIC DISTRIBUTION OF VELOCITY

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 June 7, 2001, 14:59 PARABOLIC DISTRIBUTION OF VELOCITY #1 pradeep sivakumar Guest   Posts: n/a how can i specify a parabolic distribution for inlet velocity for a 3-D elliptical jet with a major axis of 32mm and minor axis of 16mm. the maximum value of velocity is 165mm/sec. any help will be appreciated. thanks

 June 7, 2001, 20:26 Re: PARABOLIC DISTRIBUTION OF VELOCITY #2 pradeep sivakumar Guest   Posts: n/a For the above problem i am using the code FIDAP and i need help to apply the boundary conditions for inlet velocity using the module FIPREP....

 June 15, 2001, 04:01 Re: PARABOLIC DISTRIBUTION OF VELOCITY #3 Volker Pawlik Guest   Posts: n/a you have to use a udf, which defines the profile.

 June 15, 2001, 11:03 Re: PARABOLIC DISTRIBUTION OF VELOCITY #4 pradeep sivakumar Guest   Posts: n/a CAN YOU TELL ME HOW TO USE AN UDF TO DEFINE THE PROFILE?

 June 25, 2001, 07:38 Re: PARABOLIC DISTRIBUTION OF VELOCITY #5 Volker Pawlik Guest   Posts: n/a There are examples of udf available from your vendor. They can tell you, how to use them. So far: if they are simple and there is no need to compile them, you just have to provide the udf-name and the path to your cc-compiler. For examples have a look to the database for udf on cfd-online. Ask Jonas Larson (the moerator of cfd-online) where to find it. Or try this: /***********************************************/ /* Fully Developed laminar Inlet Condition */ /* for 2D-slit Problem with flow into y-direction */ /* velocity. Profile ref. to Blevins S41 Frame 1 Table 6.1*/ /* by V.Pawlik 18.04.2000 */ /***********************************************/ /*Remarks: printf except the warning, should be made to comments for final use, since the will be executed every iteration ufree means u_central, the velocity on the centerline or at the end of the boundary layer !!! */ #include "udf.h" /* coordinates of the inlet center */ /* maybe the following have to be changed X[0]=x oder X[1]=y gegen X[2]=z */ #define xc 0. #define yc 0. /* here: radius means half slit with or distance from the symmetryline to the wall */ #define radius 0.0014 /*mean velocity: (Ufree=Ucenter!!) */ #define umean 0.232 /*================================================= =================*/ DEFINE_PROFILE(z_velocity, thread, position) { float r, x[2]; face_t f; begin_f_loop(f, thread) { F_CENTROID(x,f,thread); /* 3D: r = sqrt(pow(x[0]-xc, 2)+pow(x[1]-yc, 2)); */ /* here: r means not radius but distance from the centerline or symmetryline */ r = x[0]-xc; F_PROFILE(f,thread,position)=2*umean*(1-pow(r/radius,2)); /* ************************************************** ***** */ /* controle output printf("x=%.6f\t r=%.6f\t u=%.5f\n",x[0],r,2*umean*(1-pow(r/radius,2))); */ /************************************************** *******/ } end_f_loop(f, thread) } /*================================================= ===============*/

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