{"id":377737,"date":"2024-08-08T16:22:44","date_gmt":"2024-08-08T16:22:44","guid":{"rendered":"https:\/\/innovationspace.ansys.com\/forum\/forums\/reply\/377737\/"},"modified":"2024-08-08T17:56:13","modified_gmt":"2024-08-08T17:56:13","slug":"377737","status":"publish","type":"reply","link":"https:\/\/innovationspace.ansys.com\/forum\/forums\/reply\/377737\/","title":{"rendered":"Reply To: Ansys Fluent UDF: DEFINE_DPM_BC"},"content":{"rendered":"

<p>Thanks for your reply.<\/p><p>The issue was that I did not build the udf from x86_x64 VS prompt. After opening fluent from Visual Studio prompt UDF seems to be loading without issues.<br><br>However, I have an issue where the particles in my model seem to not stick to the boundary. below I’ve copied the UDF for your reference.<br><br><br>I expected to see certain particles bounce while the rest of them to stick to the surface, here I do not see the particles bounce or stick.<\/p><p> <\/p><div><div>#include “udf.h”<\/div><div>#include “dpm.h”<\/div><div>#include “math.h”<\/div><br><div>#define Rho_air 1.225  \/* Air density in kg\/m^3 *\/<\/div><div>#define Cd 0.47        \/* Drag coefficient for a sphere *\/<\/div><div>#define mu 0.5         \/* Coefficient of friction *\/<\/div><br><div>\/* Define your boundary condition function *\/<\/div><div>DEFINE_DPM_BC(particle_bc, p, t, f, normal, dim)<\/div><div>{<\/div><div>    real V = sqrt(P_VEL(p)[0] * P_VEL(p)[0] + P_VEL(p)[1] * P_VEL(p)[1] + P_VEL(p)[2] * P_VEL(p)[2]);  \/* Velocity magnitude in m\/s *\/<\/div><br><div>    real radius = P_DIAM(p) \/ 2.0;<\/div><div>    real A = M_PI * radius * radius;  \/* M_PI is a constant for π *\/<\/div><br><div>    \/* Get the thread and cell pointers *\/<\/div><div>    Thread *t0 = P_CELL_THREAD(p);<\/div><div>    cell_t c0 = P_CELL(p);<\/div><br><div>    \/* Get local pressure at the particle’s location *\/<\/div><div>    real P_local = C_P(c0, t0);<\/div><br><div>    \/* Calculate aerodynamic force Fa *\/<\/div><div>    real Fa = 0.5 * Rho_air * A * Cd * V * V;<\/div><br><div>    \/* Calculate normal force Fn *\/<\/div><div>    real Fn = P_local * A;<\/div><br><div>    \/* Calculate frictional force Ff *\/<\/div><div>    real Ff = mu * Fn;<\/div><br><div>    \/* Coefficient of restitution *\/<\/div><div>    real e;<\/div><br><div>    if (Fa > Ff)<\/div><div>    {<\/div><div>        \/* Particle needs to bounce with a coefficient of restitution of 1 *\/<\/div><div>        e = 1.0;<\/div><br><div>        \/* Update the particle velocity to simulate the bounce *\/<\/div><div>        for (int i = 0; i < dim; i++)<\/div><div>        {<\/div><div>            P_VEL(p)[i] = -e * P_VEL(p)[i];<\/div><div>        }<\/div><br><div>        return PATH_ACTIVE; \/* No adhesion *\/<\/div><div>    }<\/div><div>    else<\/div><div>    {<\/div><div>        \/* Particle sticks to the boundary with a coefficient of restitution of 0 *\/<\/div><div>        \/\/ e = 0.0;<\/div><br><div>        \/* Update the particle velocity to simulate sticking *\/<\/div><div>        for (int i = 0; i < dim; i++)<\/div><div>        {<\/div><div>            P_VEL(p)[i] = 0;<\/div><div>        }<\/div><br><div>        P_USER_REAL(p, 0) = 1.;<\/div><div>        return PATH_ACTIVE; \/* Adhesion *\/<\/div><div>    }<\/div><div>}<\/div><\/div><p><br><br><\/p><p>Can you please comment on the code?<\/p><p> <\/p><p> <\/p><\/p>\n","protected":false},"template":"","class_list":["post-377737","reply","type-reply","status-publish","hentry"],"aioseo_notices":[],"aioseo_head":"\n\t\t\n\t\n\t\n\t\n\t\n\t\t\n\t\t\n\t\t\n\t\t\n\t\t\n\t\t\n\t\t\n\t\t\n\t\t\n\t\t\n\t\t\n\t\t\n\t\t\n\t\t\n\t\t