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[Other] Negetive Volume during mesh motion

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Old   April 9, 2015, 22:04
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  #21
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sanjeet Limbu
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I am trying to simluate the compression stroke by a piston using 2D axisymetric.
Currently i am trial s fo rthe 2D planner mesh using the dynamic mesh - profile mode, I created the profile by using the time and velocity for 1440 points from matlab taking time step as 0.000041667s.

But I am unable to get exact mesh motion. I got the zone motion correct.
The piston has crevice shape- I made two cellzone- body which defoems and crevice - as moving mesh.

I did the following: Cell zone- crevice .set as mesh motion type, and set write profile- having motion history points which also will be used for rigid bodies
Piston – as moving wall in boundary condition(piston is of two part its inteface with body and crevice both moving)
The dynamic mesh- piston as rigid body- profile selected,
Body- as deforming layering only, unchecked the remeshing and smoothening
Crevice as rigid body- profile selected.


Please tell how to do mesh also move with same distance .
I tried the UDF also but that also not working: sjows warning eror unable to read file:
#include "udf.h"
DEFINE_CG_MOTION(oscillate, dt, vel, omega, time, dtime)
{
Thread *t;
face_t f; /* define the variables */

t = DT_THREAD(dt); /* get the thread pointer for which the motion is defined */

/* if (!Data_Valid_P())
/* return; /* check if the values of the variables are accessible before you compute the function */

begin_f_loop(f, t) /* loop over each face in the zone to create an array of data */
{
if (time <= 0.02)
vel[0] = (673* time); /* define the velocity of the moving zone---*/
else if (0.02 < time < 0.027)
vel[0] = 14;
else if (0.027 < time < 0.03)
vel[0] = 3 - 2800*(time-0.03);
else if (0.03 < time)
vel[0] = 0;
}
end_f_loop(f, t)
}
Attached Images
File Type: jpg dynamic mesh setting+_preview.jpg (47.6 KB, 9 views)
File Type: jpg dynamic mesh setting4.jpg (51.9 KB, 7 views)
File Type: jpg dynamic mesh setting.jpg (43.8 KB, 5 views)
File Type: jpg dynamic mesh setting3.jpg (60.3 KB, 6 views)
File Type: jpg dynamic mesh setting2.jpg (59.3 KB, 5 views)
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Old   April 9, 2015, 22:07
Default
  #22
Member
 
sanjeet Limbu
Join Date: Mar 2015
Posts: 91
Rep Power: 11
sanjeetlimbu is on a distinguished road
hi iam getting less dynamic motion than the zone motion preview

I am trying to simluate the compression stroke by a piston using 2D axisymetric.
Currently i am trial s fo rthe 2D planner mesh using the dynamic mesh - profile mode, I created the profile by using the time and velocity for 1440 points from matlab taking time step as 0.000041667s.

But I am unable to get exact mesh motion. I got the zone motion correct.
The piston has crevice shape- I made two cellzone- body which defoems and crevice - as moving mesh.

I did the following: Cell zone- crevice .set as mesh motion type, and set write profile- having motion history points which also will be used for rigid bodies
Piston – as moving wall in boundary condition(piston is of two part its inteface with body and crevice both moving)
The dynamic mesh- piston as rigid body- profile selected,
Body- as deforming layering only, unchecked the remeshing and smoothening
Crevice as rigid body- profile selected.


Please tell how to do mesh also move with same distance .
I tried the UDF also but that also not working: sjows warning eror unable to read file:
#include "udf.h"
DEFINE_CG_MOTION(oscillate, dt, vel, omega, time, dtime)
{
Thread *t;
face_t f; /* define the variables */

t = DT_THREAD(dt); /* get the thread pointer for which the motion is defined */

/* if (!Data_Valid_P())
/* return; /* check if the values of the variables are accessible before you compute the function */

begin_f_loop(f, t) /* loop over each face in the zone to create an array of data */
{
if (time <= 0.02)
vel[0] = (673* time); /* define the velocity of the moving zone---*/
else if (0.02 < time < 0.027)
vel[0] = 14;
else if (0.027 < time < 0.03)
vel[0] = 3 - 2800*(time-0.03);
else if (0.03 < time)
vel[0] = 0;
}
end_f_loop(f, t)
}
Attached Images
File Type: jpg dynamic mesh setting+_preview.jpg (47.6 KB, 2 views)
File Type: jpg dynamic mesh setting4.jpg (51.9 KB, 3 views)
File Type: jpg dynamic mesh setting.jpg (43.8 KB, 2 views)
File Type: jpg dynamic mesh setting3.jpg (60.3 KB, 2 views)
File Type: jpg dynamic mesh setting2.jpg (59.3 KB, 1 views)
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