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UDF for calculating Oscillatory Shear Index (OSI)

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Old   February 27, 2013, 06:59
Default UDF for calculating Oscillatory Shear Index (OSI)
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Paritosh Vasava
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I am writing a UDF for calculating Oscillatory Shear Index (OSI).

The definition of OSI can be found here (right side bottom of 2nd page)
http://utopia.duth.gr/~soulis/Public...0of%20Non-.pdf

Any hint or help about this?
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Old   October 15, 2013, 09:53
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I'm trying to do the same actually
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Old   October 22, 2014, 08:02
Default osi in Fluent
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hi dear colleague, to calculate the shear oscillation index in FLUENT I found these two links:

http://www.cfd-online.com/Forums/flu...ng-fluent.html
http://cape-forum.com/index.php/topic,1074.0.html

but in the second link the colleague "infocfd" is about a UDF attached, but I can’t download it ... if you can download the UDF or help me to understand the principle of calculated OSI on FLUENT please answer me ... thank you for your cooperation.

Last edited by wyldckat; October 26, 2014 at 12:22. Reason: fixed Google'lized links
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Old   October 23, 2014, 02:46
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Sorry but I cant download it either. Anyways I calculated OSI with matlab however visualization of the calculated is still an issue for us.
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Old   October 29, 2015, 04:24
Default Osi udf
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Hello Guys,

I did some work in this field awhile ago, you can use the attached UDF I wrote for my uses back then.

Hope it helps, and yeah I know this one is an oldie...

Regards.
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File Type: c osi.c (1.7 KB, 454 views)
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Old   November 18, 2015, 02:39
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I will give it a try. Thanks Khuti!
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Old   November 25, 2015, 05:49
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Thank you, Khuti.
I want to clarify if the OSI values are area-averaged.
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Old   December 20, 2015, 05:33
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Hi Dhplsy,

Sorry for the delayed response.

The values that are being used in the calculation are taken from the Fluent raw data storage, so they are per cell face and averaged by the relevant cell face area.

Also please note, that you might want to delete some of the code related to the names of the UDM:

DEFINE_EXECUTE_ON_LOADING(nameinit, libudf)
{
Set_User_Memory_Name(0, "uWSS");
Set_User_Memory_Name(1, "uWSSx");
Set_User_Memory_Name(2, "uWSSy");
Set_User_Memory_Name(3, "uWSSz");
Set_User_Memory_Name(4, "OSI");
}

( as I remember it caused some problems, hadn't the chance to figure out what was the problem)

Enjoy!
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Old   October 26, 2019, 16:20
Exclamation Osi udf
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Hello,
I've been used the UDF above. I don't understand why the WSS values are not in good agreement as those automatically calculated by Fluent. Consequently, the calculation of OSI is not consistent ... Has anyone solved this problem?


Thanks
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Old   January 3, 2020, 06:22
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Quote:
Originally Posted by khuti View Post
Hello Guys,

I did some work in this field awhile ago, you can use the attached UDF I wrote for my uses back then.

Hope it helps, and yeah I know this one is an oldie...

Regards.
Can you give me?Thank you
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Old   August 11, 2021, 06:13
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hello KHUTI,
I am confused, i interpret the UDF you had provided and run the simulation but after solution is complete, where did the result of OSI has been saved?
please suggest the correct way

thank you
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Old   August 12, 2021, 00:48
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go to contours
-> contours of
-> user -defined memory
-> select "OSI" (also it could be udm-4)
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Old   August 12, 2021, 01:22
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Quote:
Originally Posted by AlexanderZ View Post
go to contours
-> contours of
-> user -defined memory
-> select "OSI" (also it could be udm-4)
thank you Alexander Z
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Old   August 16, 2021, 03:19
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Quote:
Originally Posted by AlexanderZ View Post
go to contours
-> contours of
-> user -defined memory
-> select "OSI" (also it could be udm-4)
Dear Alexander sir,
could you please explain it in detail. because I have tried it by interpreting the UDF in Fluent. then in contours drobox I didn't found any user-defined option.
please help
thank you
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Old   August 17, 2021, 13:42
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You have to make a new contour first.
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"The UDF library you are trying to load (libudf) is not compiled for parallel use on the current platform" is NOT the error after compiling. It is the error after loading. To see compiler errors, look at your screen after you click "build".
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Old   August 5, 2022, 16:23
Default time averaged values
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Hi All,
For using the code :
DEFINE_EXECUTE_AT_END(OSI)
{
Domain *domain;
real area;
face_t f;
real A[ND_ND];
cell_t c, c0;
Thread *t,*t0, *c_thread;
real wallshear [ND_ND];

domain = Get_Domain(domain_ID);
t = Lookup_Thread(domain,zone_ID);

begin_f_loop(f, t)
{
F_AREA(A,f,t);
area = NV_MAG(A);
NV_V(wallshear,=,F_STORAGE_R_N3V(f,t, SV_WALL_SHEAR));
c0 = F_C0(f,t);
t0 = THREAD_T0(t);
C_UDMI(c0,t0,0) += NV_MAG(wallshear)/area;
C_UDMI(c0,t0,1) += -wallshear[0]/area;
C_UDMI(c0,t0,2) += -wallshear[1]/area;
C_UDMI(c0,t0,3) += -wallshear[2]/area;
C_UDMI(c0,t0,4) = (1.-sqrt(C_UDMI(c0,t0,1)*C_UDMI(c0,t0,1) + C_UDMI(c0,t0,2)*C_UDMI(c0,t0,2) + C_UDMI(c0,t0,3)*C_UDMI(c0,t0,3))/C_UDMI(c0,t0,0))/2;
}
end_f_loop(f,t)
}


In Fluent must be enabled Data Sampling for Time Statistics and defined CFFs = UDM(0),...(4) ? In this way unsteady statistics(such time averaged) results are available for the UDMs ?
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Old   October 19, 2022, 04:07
Default Contour of OSI
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Quote:
Originally Posted by AlexanderZ View Post
go to contours
-> contours of
-> user -defined memory
-> select "OSI" (also it could be udm-4)
Hello Alexander
I try to calculate "osi" and i compiled this udf
After finished run, i go to contours and select OSI but any thing is showing!!
What's the problem??
Thank you
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Old   October 19, 2022, 04:55
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in case you could select OSI inside contours menu everything is OK.
may be you are using wrong settings for contours

if you still have problems, show your code, compilation log, whats fluent version you are using, explain how you are making contours
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Old   October 19, 2022, 08:22
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Quote:
Originally Posted by AlexanderZ View Post
in case you could select OSI inside contours menu everything is OK.
may be you are using wrong settings for contours

if you still have problems, show your code, compilation log, whats fluent version you are using, explain how you are making contours
Code:/************************************************** ****
Oscillatory shear index
************************************************** ****/

#include "udf.h"
#include "math.h"
#include "storage.h"
#include "sg_udms.h"

#define domain_ID 1
#define zone_ID 7

/* Define Names for the WSS UDMI and its components */
DEFINE_EXECUTE_ON_LOADING(nameinit, libudf)
{
Set_User_Memory_Name(0, "uWSS");
Set_User_Memory_Name(1, "uWSSx");
Set_User_Memory_Name(2, "uWSSy");
Set_User_Memory_Name(3, "uWSSz");
Set_User_Memory_Name(4, "OSI");
}


/* Initialize the UDM value to zero in complete domain */
DEFINE_INIT(meminit,domain)
{
Thread *c_thread;
cell_t c;

thread_loop_c(c_thread,domain)
{
begin_c_loop(c, c_thread)
{
C_UDMI(c,c_thread,0)= 0;
C_UDMI(c,c_thread,1)= 0;
C_UDMI(c,c_thread,2)= 0;
C_UDMI(c,c_thread,3)= 0;
C_UDMI(c,c_thread,4)= 0;
}
end_c_loop(c, c_thread)
}
}

/* Calculate wall shear stress and store them in UDM */
DEFINE_EXECUTE_AT_END(OSI)
{
Domain *domain;
real area;
face_t f;
real A[ND_ND];
cell_t c, c0;
Thread *t,*t0, *c_thread;
real wallshear [ND_ND];

domain = Get_Domain(domain_ID);
t = Lookup_Thread(domain,zone_ID);

begin_f_loop(f, t)
{
F_AREA(A,f,t);
area = NV_MAG(A);
NV_V(wallshear,=,F_STORAGE_R_N3V(f,t, SV_WALL_SHEAR));
c0 = F_C0(f,t);
t0 = THREAD_T0(t);
C_UDMI(c0,t0,0) += NV_MAG(wallshear)/area;
C_UDMI(c0,t0,1) += -wallshear[0]/area;
C_UDMI(c0,t0,2) += -wallshear[1]/area;
C_UDMI(c0,t0,3) += -wallshear[2]/area;
C_UDMI(c0,t0,4) = (1.-sqrt(C_UDMI(c0,t0,1)*C_UDMI(c0,t0,1) + C_UDMI(c0,t0,2)*C_UDMI(c0,t0,2) + C_UDMI(c0,t0,3)*C_UDMI(c0,t0,3))/C_UDMI(c0,t0,0))/2;
}
end_f_loop(f,t)
}

I compiled udf with visual studio 2010
Fluent version: 19R3
I go to contours>>new contour
Location:wall body
Variable:OSI>>apply
But range of osi display is 0.0-0.0
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Old   October 21, 2022, 03:21
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code seems to be correct
did you hook functions in fluent GUI?
user-defined - > function hooks
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