# DPM mass flow rate

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 LinkBack Thread Tools Search this Thread Display Modes May 4, 2004, 10:50 DPM mass flow rate #1 Szabolcs Varga Guest   Posts: n/a Dear all, The particle mass flow rate is defined at the injection panel. I wrote a UDF where the I use the function(see the whole udf below): C_UDMI(c,t,p_frate)=P_FLOW_RATE(p) to store particle flow rate in a user memory for each cell. After solution, the values summed in the surface integral panel e.g over the outlet (any closed surface around the injection point) should give the total injection mass flow rate, shouldn't it? In my model it doesn´t. Could you help me please what I might be doing wrong? /* UDF for computing the magnetic force on a charged particle */ #include "udf.h" #include "surf.h" #define charge_per_meter 1.6e-11 /* particle electric charge */ DEFINE_DPM_BODY_FORCE(particle_l_forcemod, p, i) { cell_t c = RP_CELL(&(p->cCell)); Thread *t = RP_THREAD(&(p->cCell)); real l_force, mp, ex_t, er_t, Elp; real charge_on_p; int V_x=0, V_r=1, E_x=0, E_r=1, numb_part=3, p_frate=4, p_m=5; mp=P_MASS(p); C_UDMI(c,t,p_frate)=P_FLOW_RATE(p); C_UDMI(c,t,p_m)=P_MASS(p); C_UDMI(c,t,numb_part)=P_FLOW_RATE(p)/P_MASS(p); charge_on_p= P_DIAM(p)*charge_per_meter; ex_t=C_UDMI(c,t,E_x); er_t=C_UDMI(c,t,E_r);  May 4, 2004, 14:02 Re: DPM mass flow rate #2 Allan Walsh Guest   Posts: n/a I'm not sure it should add up. Be careful that the units are the same for both variables - and how would you factor in residence time for the particles in Lagrangian form.  May 5, 2004, 06:08 Re: DPM mass flow rate #3 Szabolcs Varga Guest   Posts: n/a Dear Alan, Thank you for your answer. I checked again the UDF manual, and it says that the P_FLOW_RATE(p) returns the particle mass P_MASS(p) times the number of particles in this stream (p) that passes a particular point in a second. It should give kg/s. My doubt is that, if there are two streams in the same cell, does it sum up? How can I caculate the total mass flow rate of particles in each cell? The problem is relatively simple, it is a conduct with and injection surface and an outlet surface. The particles are tracked in between these two. In principle every cross section should have the same mass flow rate both particles and fluid. When Fluent gives me the summary at the end of the particle tracking, the flow rates at the injection and escape boundary (no trap in between) match, but not using the sum of the P_FLOW_RATE(p) over the outlet surface. I am certain that I am doing something incorrectly, but cannot figure out what. Finest regards, Szabolcs  May 6, 2004, 15:21 Re: DPM mass flow rate #4 Allan Walsh Guest   Posts: n/a There is a difference between the particle mass and the fraction of the total particle mass represented by each drop. For example, a particle may have a mass of 0.001 kg but represent say 10% of the particle mass flow rate of say 1 kg/s for 0.1 kg/s. Thread Tools Search this Thread Show Printable Version Email this Page Search this Thread: Advanced Search Display Modes Linear Mode Switch to Hybrid Mode Switch to Threaded Mode Posting Rules You may not post new threads You may not post replies You may not post attachments You may not edit your posts BB code is On Smilies are On [IMG] code is On HTML code is OffTrackbacks are Off Pingbacks are On Refbacks are On Forum Rules Similar Threads Thread Thread Starter Forum Replies Last Post a.lynchy Fluent UDF and Scheme Programming 31 October 4, 2018 14:10 wildli FLUENT 2 July 8, 2015 11:38 Vashishth Patel CFX 7 April 3, 2014 20:33 Rhinocao FLUENT 3 January 21, 2011 12:10 Masood FLUENT 0 May 22, 2005 00:32

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