Try UDF (User Defined Function),

here is an example of the oscillatory UDF.

#include "udf.h"

#define Freq 1.0

#define angular_freq 2.0*M_PI*Freq

#define tetoscille 20.0*M_PI/180

DEFINE_CG_MOTION(shm, dt, cg_vel, cg_omega, time, dtime)

{

cg_vel[0] = 0.0;

cg_vel[1] = 0.0;

cg_vel[2] = 0.0; l

cg_omega[0] = 0;

cg_omega[1] = tetoscille*cos(angular_freq*time);

cg_omega[2] = 0.0;

}

if your motion is angular use cg_omega and if it linear use cg_vel.

oscillation needs structural model on like linear elasticity

To calculate the Oscillatory Shear Index (OSI) in ANSYS Fluent without using a User Defined Function (UDF), you can use the available post-processing capabilities of Fluent, although it may not be as straightforward as in some other software. The OSI quantifies the unsteady or oscillatory nature of the shear stress in a flow and is often used in studies of turbulence and flow behavior.

The formula for the OSI is typically:

OSI=∣τmax∣−∣τmin∣∣τmax∣+∣τmin∣OSI = \frac{|\tau_{max}| - |\tau_{min}|}{|\tau_{max}| + |\tau_{min}|}OSI=∣τmax​∣+∣τmin​∣∣τmax​∣−∣τmin​∣​

Where:

• τmax\tau_{max}τmax​ and τmin\tau_{min}τmin​ are the maximum and minimum shear stress values over a period of time.

Steps to compute OSI in Fluent:

While Fluent doesn’t provide a direct built-in method to compute OSI in the post-processing stage without using a UDF, using its surface monitor tools and exporting time data allows you to calculate OSI externally. If you'd prefer more automation, using a UDF or a scripting approach within Fluent would be more efficient, but this method works as a practical workaround.

Hi. You can send me message and I will provide you with the correct method for calculation of the OSI.

Ashkan Ghafari sorry i am new to research gate could you please messame me the method on how to calculate OSI please