# Calculate the entering flow rate in each cell

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 February 21, 2012, 05:21 Calculate the entering flow rate in each cell #1 Member   Join Date: Apr 2010 Posts: 53 Rep Power: 5 Hi at all! I am trying to find a way how to calculate the flow rate that enters or leaves a cell. In sum it should be zero but I like to find out a specific value for each cell of the domain. Does anyone has an idea how to approach this? Thank you very much in advance.

February 21, 2012, 21:11
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Ji Junjie
Join Date: Feb 2010
Location: Shanghai, China
Posts: 97
Rep Power: 6
Quote:
 Originally Posted by bephi Hi at all! I am trying to find a way how to calculate the flow rate that enters or leaves a cell. In sum it should be zero but I like to find out a specific value for each cell of the domain. Does anyone has an idea how to approach this? Thank you very much in advance.
loop over the faces of a cell, and calculate the sum of flux through these faces

 May 30, 2012, 12:11 problem trying to get the mass flow entering a cell #3 New Member   javiercran Join Date: May 2012 Posts: 2 Rep Power: 0 Hello, I have tried to calculate the mass flow entering inside a cell (for a DEFINE_SOURCE macro) with a loop over the faces of the cell but I have problems of "non-integer subscript expression: unsigned char". This is my code #include "udf.h" #include DEFINE_SOURCE(theta_momentum,c,t,dS,eqn) { //near peak operating point real Ft; //Ft source term real T01; //Inlet Total temperature real T02; //Outlet Total temperature real cp; //variable which will store the specific heat of air real x[ND_ND]; //array for storing the centroid position real pi=3.1416; real omega=16043*2*pi/60; real r; face_t f; real massflow=0; real volume; Thread *f_thread; int n; c_face_loop(c,t,n)//line 21 the one which gives problems {f=C_FACE(c,t,n); f_thread = C_FACE_THREAD(c,t,n); if(F_FLUX(f,f_thread)>0)// only calculate the massflow entering {massflow=massflow+F_FLUX(f,f_thread); } } massflow=massflow*2*pi;//axisymmetric volume=C_VOLUME(c,t); T01=288.15; cp=1006; C_CENTROID(x,c,t);//we store in x the centroid position of each cell r=x[1];// the radial position is the y-coordinate of the cell centroid r = x[1]; T02=1.164*T01; Ft=massflow*cp*(T02-T01)/(volume*omega*r); dS[eqn]=0; return Ft; } I need your help because I cant see the mistake I am doing. Regards

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