DPM UDF particle position using the macro P_POS(p)[i]

 Register Blogs Members List Search Today's Posts Mark Forums Read

 April 17, 2009, 01:29 DPM UDF particle position using the macro P_POS(p)[i] #1 New Member   Min Du Join Date: Apr 2009 Posts: 1 Rep Power: 0 Sponsored Links Hello everybody, I have a problem when I use the macro P_POS(p) to get the particle positions. I want to calculate the particle collisions using macro DEFINE_DPM_SPRAY_COLLIDE. As the first try, I want to obtain the particle positions and velocities using the following simple UDF. DEFINE_DPM_SPRAY_COLLIDE(collide,tp,p) { Message("-----------------------------\n"); Message("particle position: %10f, %10f, %10f; velocity: º%10f, %10f, %10f; time step: º%10f\n", P_POS(tp)[0], P_POS(tp)[1], P_POS(tp)[2], P_VEL(tp)[0], P_VEL(tp)[1], P_VEL(tp)[2], P_DT(tp)); } I can obtain two groups of results after every time step: (two particle injected in the calculation domain for every time step) After the first time step Results from UDF in the console window : ----------------------------- particle position: 0.499532, 0.001013, 0.739735; velocity: -37.015999, 0.008046, 0.012735; time step: 0.000050 ----------------------------- particle position: 0.499002, 0.006400, 0.749981; velocity: -37.025082, -0.011640, -0.014559; time step: 0.000050 number tracked = 2, escaped = 0, aborted = 0, trapped = 0, evaporated = 0, incomplete = 0, coalesced = 0 These results below are obtained from DPM reports following the steps. DisplayàParticle tracksàReport Type: Current Positions and Report to: ConsoleàTrack Time X-Position Y-Position Z-Position X-Velocity Y-Velocity Z-Velocity 4.95911e-005 4.97682e-001 1.01297e-003 7.39736e-001 -3.70160e+001 8.04605e-003 1.27348e-002 4.95911e-005 4.97151e-001 6.39963e-003 7.49980e-001 -3.70251e+001 -1.16404e-002 -1.45594e-002 After the second time step Results from UDF in the console window : ----------------------------- particle position: 0.498317, 0.001916, 0.765399; velocity: -37.018932, -0.005328, 0.000110; time step: 0.000050 ----------------------------- particle position: 0.499558, 0.002685, 0.760411; velocity: -37.015694, -0.006167, -0.002309; time step: 0.000050 ----------------------------- particle position: 0.497682, 0.001013, 0.739736; velocity: -37.031860, 0.016161, 0.025296; time step: 0.000050 ----------------------------- particle position: 0.497151, 0.006400, 0.749980; velocity: -37.049992, -0.023105, -0.029179; time step: 0.000050 number tracked = 4, escaped = 0, aborted = 0, trapped = 0, evaporated = 0, incomplete = 0, coalesced = 0 These results below are obtained from DPM reports using the same method mentioned above. Time X-Position Y-Position Z-Position X-Velocity Y-Velocity Z-Velocity 4.95911e-005 4.96467e-001 1.91631e-003 7.65399e-001 -3.70189e+001 -5.32831e-003 1.09906e-004 4.95911e-005 4.97707e-001 2.68470e-003 7.60411e-001 -3.70157e+001 -6.16660e-003 -2.30891e-003 9.91821e-005 4.95831e-001 1.01357e-003 7.39737e-001 -3.70319e+001 1.61610e-002 2.52956e-002 9.91821e-005 4.95299e-001 6.39876e-003 7.49979e-001 -3.70500e+001 -2.31050e-002 -2.91788e-002 Results after the third time step as the same: ----------------------------- particle position: 0.496467, 0.001916, 0.765399; velocity: -37.037704, -0.010518, 0.000321; time step: 0.000050 ----------------------------- particle position: 0.497707, 0.002685, 0.760411; velocity: -37.031239, -0.012192, -0.004506; time step: 0.000050 ----------------------------- particle position: 0.495831, 0.001014, 0.739737; velocity: -37.047588, 0.024344, 0.037684; time step: 0.000050 ----------------------------- particle position: 0.495299, 0.006399, 0.749979; velocity: -37.074730, -0.034395, -0.043858; time step: 0.000050 ----------------------------- particle position: 0.498798, 0.001538, 0.747872; velocity: -37.028553, -0.010786, 0.016159; time step: 0.000050 ----------------------------- particle position: 0.497937, -0.006550, 0.742732; velocity: -37.006294, 0.012822, -0.013909; time step: 0.000050 number tracked = 6, escaped = 0, aborted = 0, trapped = 0, evaporated = 0, incomplete = 0, coalesced = 0 Time X-Position Y-Position Z-Position X-Velocity Y-Velocity Z -Velocity 9.91821e-005 4.94615e-001 1.91591e-003 7.65399e-001 -3.70377e+001 -1.05180e-002 3.21468e-004 9.91821e-005 4.95856e-001 2.68424e-003 7.60411e-001 -3.70312e+001 -1.21916e-002 -4.50621e-003 1.48773e-004 4.93979e-001 1.01459e-003 7.39738e-001 -3.70476e+001 2.43444e-002 3.76838e-002 1.48773e-004 4.93446e-001 6.39733e-003 7.49977e-001 -3.70747e+001 -3.43949e-002 -4.38583e-002 4.95911e-005 4.96948e-001 1.53728e-003 7.47873e-001 -3.70286e+001 -1.07858e-002 1.61592e-002 4.95911e-005 4.96087e-001 -6.55002e-003 7.42732e-001 -3.70063e+001 1.28220e-002 -1.39095e-002 The particle velocity for a particle from two groups of results after every time step is the same, which is correct. The problem is that the particle position for a particle from two groups of results after every time step is different. From the calculation results, it is seems that the macro P_POS(p)[i] gets the particle position at the end of the previous time step. How can I get the particle position now in UDF. Thank you in advance. DuMin abdualmagid likes this. Last edited by dm2747; April 17, 2009 at 04:06. Reason: to read easily

 Tags dpm, particle position, p_pos(p), udf

 Thread Tools Display Modes Linear 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 On Pingbacks are On Refbacks are On Forum Rules

 Similar Threads Thread Thread Starter Forum Replies Last Post Tom FLUENT 8 July 25, 2015 12:30 sohail FLUENT 0 July 22, 2008 10:12 Laika FLUENT 6 January 23, 2006 00:40 Puneet FLUENT 3 November 28, 2003 11:55 cfdfans FLUENT 4 April 2, 2001 05:03