{"id":373881,"date":"2024-07-28T14:38:54","date_gmt":"2024-07-28T14:38:54","guid":{"rendered":"https:\/\/innovationspace.ansys.com\/forum\/forums\/topic\/simulating-selective-laser-melting-process-in-ansys-fluent-udf-issue\/"},"modified":"2024-07-28T14:38:54","modified_gmt":"2024-07-28T14:38:54","slug":"simulating-selective-laser-melting-process-in-ansys-fluent-udf-issue","status":"closed","type":"topic","link":"https:\/\/innovationspace.ansys.com\/forum\/forums\/topic\/simulating-selective-laser-melting-process-in-ansys-fluent-udf-issue\/","title":{"rendered":"Simulating Selective Laser Melting process in Ansys Fluent – UDF issue"},"content":{"rendered":"

I am simulating the Selective Laser Melting (SLM) process in Ansys Fluent. I have designed the powder bed domain (along with the gas domain) with dimensions of 0.8 mm (x) x 0.2 mm (z) x 0.28 mm (y). During initialization, I patched<\/strong> the region with a height of 0.2 mm along the Y-axis as solid, and the rest as the gas domain, as shown in the image.<\/p>\n

I need to apply a laser heat source at the interface of the solid-gas contact surface<\/strong> and also apply recoil pressure and Marangoni effect equations. I understand that a UDF is required for this. I found a UDF code from one of the posts in this forum (which does not include the Marangoni effect) which I have added at last part of the post. <\/p>\n

 <\/p>\n

Here are my questions:<\/div>\n
 <\/div>\n
1. Material Properties Usage:<\/strong> If density and specific heat data are specified within the UDF, what is the use of the material properties defined in the “Materials” section inside Fluent? How does Fluent determine which properties to use during the simulation?<\/em><\/div>\n
 <\/div>\n
2. UDF Implementation Issue:<\/strong> I successfully compiled the code within ANSYS, hooked it under the Adjust section, and added the heat source term under the Cell Zone Boundary Condition. However, I don’t see any changes in the results (i.e the phase shape does not change from the initial state) . I even defined 12 User-Defined Memory (UDM) locations. Can you help me identify what might have gone wrong?<\/em><\/div>\n
 <\/div>\n
\n
UDF Code : <\/span><\/strong><\/div>\n
 <\/div>\n
 <\/div>\n
 <\/div>\n
#include “udf.h”<\/div>\n
#include “sg_mphase.h”<\/div>\n
#include “mem.h”<\/div>\n
#include “sg_mem.h”<\/div>\n
#include “math.h”<\/div>\n
#include “flow.h”<\/div>\n
#include “unsteady.h”<\/div>\n
#include “metric.h”<\/div>\n
 <\/div>\n
#define A 0.4 \/\/ Absorption coefficient<\/div>\n
#define P 200 \/\/ Laser power<\/div>\n
#define R 80e-6 \/\/ Spot radius<\/div>\n
#define v 0.1 \/\/ Scan speed of laser<\/div>\n
#define h 25 \/\/ Heat transfer coefficient<\/div>\n
#define Ta 300 \/\/ Ambient air temperature<\/div>\n
#define s 5.67e-8 \/\/ Stefan Boltzmann constant<\/div>\n
#define e 0.5 \/\/ Emissivity<\/div>\n
#define Pi 3.1415926535<\/div>\n
#define Ts 1658 \/\/ Solidus temperature<\/div>\n
#define Tl 1723 \/\/ Liquidus temperature<\/div>\n
#define x0 0.0\/\/ Initial x position of the laser<\/div>\n
#define y0 0.1e-3 \/\/ Initial y position of the laser<\/div>\n
#define Lv 7.45e6 \/\/ Latent heat of Vaporisation<\/div>\n
#define Tv 3090 \/\/ Evaporation Temperature<\/div>\n
#define Rg 8.314 \/\/ Universal Gas constant<\/div>\n
#define M 0.005593 \/\/ Molar mass<\/div>\n
#define Pa 101325 \/\/ Atmospheric pressure<\/div>\n
#define domain_ID 3 \/\/ Domain ID of metal substrate<\/div>\n
 <\/div>\n
DEFINE_ADJUST(adjust_gradient, domain)<\/div>\n
{<\/div>\n
    Thread *t;<\/div>\n
    Thread **pt;<\/div>\n
    cell_t c;<\/div>\n
    int phase_domain_index = 1.0;<\/div>\n
    Domain *pDomain = DOMAIN_SUB_DOMAIN(domain,phase_domain_index);<\/div>\n
    {<\/div>\n
        Alloc_Storage_Vars(pDomain,SV_VOF_RG,SV_VOF_G,SV_NULL);<\/div>\n
        Scalar_Reconstruction(pDomain, SV_VOF,-1,SV_VOF_RG,NULL);<\/div>\n
        Scalar_Derivatives(pDomain,SV_VOF,-1,SV_VOF_G,SV_VOF_RG, Vof_Deriv_Accumulate);<\/div>\n
    }<\/div>\n
    mp_thread_loop_c(t,domain,pt)<\/div>\n
    if (FLUID_THREAD_P(t))<\/div>\n
    {<\/div>\n
        Thread *ppt = pt[phase_domain_index];<\/div>\n
        begin_c_loop (c,t)<\/div>\n
        {<\/div>\n
            C_UDMI(c,t,0) = C_VOF_G(c,ppt)[0];<\/div>\n
            C_UDMI(c,t,1) = C_VOF_G(c,ppt)[1];<\/div>\n
            C_UDMI(c,t,2) = C_VOF_G(c,ppt)[2];<\/div>\n
            C_UDMI(c,t,3) = sqrt(C_UDMI(c,t,0)*C_UDMI(c,t,0) + C_UDMI(c,t,1)*C_UDMI(c,t,1) + C_UDMI(c,t,2)*C_UDMI(c,t,2));<\/div>\n
        }<\/div>\n
        end_c_loop (c,t)<\/div>\n
    }<\/div>\n
    Free_Storage_Vars(pDomain,SV_VOF_RG,SV_VOF_G,SV_NULL);<\/div>\n
}<\/div>\n
 <\/div>\n
 <\/div>\n
 <\/div>\n
DEFINE_SOURCE(heat_source, c, t, dS, eqn)<\/div>\n
{<\/div>\n
    Thread *pri_th;<\/div>\n
    Thread *sec_th;<\/div>\n
    real source;<\/div>\n
    real x[ND_ND], time;<\/div>\n
    time = CURRENT_TIME;<\/div>\n
    C_CENTROID(x, c, t);<\/div>\n
    real T = C_T(c,t);<\/div>\n
    <\/div>\n
    pri_th = THREAD_SUB_THREAD(t, 0);<\/div>\n
    sec_th = THREAD_SUB_THREAD(t, 1);<\/div>\n
    <\/div>\n
    real alpha = C_VOF(c,sec_th); \/\/ Use sub-thread for cell volume fraction<\/div>\n
    real gamma = C_LIQF(c,sec_th); \/\/ Use sub-thread for cell liquid fraction<\/div>\n
    <\/div>\n
    real Pv = 0.54*Pa*exp((Lv*M*(T-Tv))\/(Rg*T*Tv));<\/div>\n
    real mv = (0.82*M*Pv)\/(sqrt(2*Pi*M*Rg*T));<\/div>\n
    real rhog = 1.6228; \/\/ Density of argon<\/div>\n
    real rhos = 7900; \/\/ Density of solid SS316<\/div>\n
    real rhol = 7433 + 0.0393*T – 0.00018*pow(T,2); \/\/ Density of liquid SS316<\/div>\n
    real rhom = rhol*gamma + rhos*(1-gamma); \/\/ Density of SS316<\/div>\n
    real rho = alpha*rhom + rhog*(1-alpha); \/\/ Density of cell containing metal and gas<\/div>\n
    real Cpg = 520.64; \/\/ Specific heat of argon<\/div>\n
    real Cps = 462 + 0.134*T; \/\/ Specific heat of solid SS316<\/div>\n
    real Cpl = 775; \/\/ Specific heat of liquid SS316<\/div>\n
    real Cpm = Cpl*gamma + Cps*(1-gamma); \/\/ Specific heat of SS316<\/div>\n
    real Cp = alpha*Cpm + Cpg*(1-alpha); \/\/ Specific heat of cell containing metal and gas<\/div>\n
    real factor = (2*rho*Cp)\/(rhom*Cpm + rhog*Cpg);<\/div>\n
 <\/div>\n
    if(C_VOF(c,sec_th) > 0.05 && C_VOF(c,sec_th) < 1)<\/div>\n
    {<\/div>\n
        if(C_T(c,sec_th) < 3090)<\/div>\n
        {<\/div>\n
            source = (((2*A*P)\/(Pi*R*R))*exp((-2*(pow(x[0]-x0-v*time,2.) + pow(x[1]-y0,2.)))\/(R*R)) – h*(T-Ta) – s*e*(pow(T,4.) – pow(Ta,4.)))*C_UDMI(c,t,3)*factor;<\/div>\n
            dS[eqn] = 0.0;<\/div>\n
        }<\/div>\n
        else if(C_T(c,sec_th) >= 3090)<\/div>\n
        {<\/div>\n
            source = (((2*A*P)\/(Pi*R*R))*exp((-2*(pow(x[0]-x0-v*time,2.) + pow(x[1]-y0,2.)))\/(R*R)) – h*(T-Ta) – s*e*(pow(T,4.) – pow(Ta,4.)) – Lv*mv)*C_UDMI(c,t,3)*factor;<\/div>\n
            dS[eqn] = 0.0;<\/div>\n
        }<\/div>\n
    }<\/div>\n
    else<\/div>\n
    {<\/div>\n
        source = 0.0;<\/div>\n
        dS[eqn] = 0.0;<\/div>\n
    }<\/div>\n
    return source;<\/div>\n
}<\/div>\n

 <\/p>\n<\/div>\n

 <\/div>\n

 <\/p>\n

 <\/p>\n","protected":false},"template":"","class_list":["post-373881","topic","type-topic","status-closed","hentry","topic-tag-fluent-ansys-1","topic-tag-multiphase","topic-tag-SLM-1","topic-tag-udf","topic-tag-vof"],"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