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June 13, 2012, 06:58 |
pressure profile behind projectile
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#1 |
New Member
Marta
Join Date: Mar 2012
Location: Warsaw
Posts: 4
Rep Power: 14 |
Hi, I have a problem with my simulation. I have to get the proper conduct of the pressure for a missile. But I have no formula for the pressure, only the results of another simulation in *. txt. This pressure is exerted on the bottom of the projectile. I tried to get them through UDF'a, but I get the error:
cpp -I"c:\ANSYSI~1\v121\fluent\fluent12.1.4/src" -I"c:\ANSYSI~1\v121\fluent\fluent12.1.4/cortex/src" -I"c:\ANSYSI~1\v121\fluent\fluent12.1.4/client/src" -I"c:\ANSYSI~1\v121\fluent\fluent12.1.4/multiport/src" -I. -DUDFCONFIG_H="<udfconfig.h>" "D:\ANSYS_p ojekt\ETAP III\pbase.c.txt" Error: D:\ANSYS_projekt\ETAP III\pbase.c.txt: line 16: parse error. Error: D:\ANSYS_projekt\ETAP III\pbase.c.txt: line 24: parse error. This is my UDF: /************************************************** ******************** unsteady.c UDF for specifying a transient parameters profile boundary condition ************************************************** *********************/ #include "udf.h" DEFINE_PROFILE(unsteady_pressure, thread, position) { face_t f; real t = CURRENT_TIME; if (t <= 0.00084315) { begin_f_loop(f, thread) { F_PROFILE(f, thread, position) = -14 275 547 954 749 500 000 000.0*t*t*t*t*t*t + 43 436 065 414 501 600 000.0*t*t*t*t*t - 48 268 301 672 906 800.0*t*t*t*t + 23 694 384 396 288.0*t*t*t - 4 644 259 507.75*t*t + 469 948.4355*t + 36.8189; } end_f_loop(f, thread) } else { begin_f_loop(f, thread) { F_PROFILE(f, thread, position) = 5 315 344 214 775 300.0*t*t*t*t*t - 78 873 823 528 841.0*t*t*t*t + 435 375 156 550.906*t*t*t - 1 075 741 334.8709*t*t + 1 046 010.0566*t - 39.2758; } end_f_loop(f, thread) }} (I am a layman in writing UDF: () I do not think it worked, but I have other ideas how to figure it out. If anyone has any idea how to move, I will be grateful. Waiting for information Regards |
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June 13, 2012, 12:34 |
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#2 |
Senior Member
Rick
Join Date: Oct 2010
Posts: 1,016
Rep Power: 26 |
Here is your udf:
Code:
#include "udf.h" DEFINE_PROFILE(unsteady_pressure, thread, position) { face_t f; real t = CURRENT_TIME; begin_f_loop(f, thread) { if (t <= 0.00084315) F_PROFILE(f, thread, position) = -14275547954749500000000.0*t*t*t*t*t*t+43436065414501600000.0*t*t*t*t*t-48268301672906800.0*t*t*t*t+23694384396288.0*t*t*t-4644259507.75*t*t+469948.4355*t+36.8189; else F_PROFILE(f, thread, position) = 5315344214775300.0*t*t*t*t*t-78873823528841.0*t*t*t*t+435375156550.906*t*t*t-1075741334.8709*t*t+1046010.0566*t-39.2758; } end_f_loop(f, thread) } Copy and name it whatyouwant.c Daniele |
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June 19, 2012, 04:38 |
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#3 |
New Member
Marta
Join Date: Mar 2012
Location: Warsaw
Posts: 4
Rep Power: 14 |
Thanks,
It looks fine. But I have another problem because projectile moves through the six DOF and this UDF is compiled. When I'm using the UDF with pressure profile behind the projectile then I have a message that "the six DOF can not be negative mass". Does anyone know how to combine these two UDFs or has any idea how I can enter the desired pressure profile for a missile while taking advantage of its six DOF motion? Waiting for information Regards |
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