{"id":311895,"date":"2023-10-17T17:48:47","date_gmt":"2023-10-17T17:48:47","guid":{"rendered":"\/forum\/forums\/topic\/udfs-for-adding-energy-source-term-in-pcm-in-porous-medium\/"},"modified":"2023-10-17T17:48:47","modified_gmt":"2023-10-17T17:48:47","slug":"udfs-for-adding-energy-source-term-in-pcm-in-porous-medium","status":"closed","type":"topic","link":"https:\/\/innovationspace.ansys.com\/forum\/forums\/topic\/udfs-for-adding-energy-source-term-in-pcm-in-porous-medium\/","title":{"rendered":"UDFs for adding Energy source term in PCM in Porous medium"},"content":{"rendered":"

Hello, I am unsure if this is the place to ask this, however I am really struggling to create UDFs to fit a numerical model which must be applied as UDFs in ANSYS Fluent to model a phase change material in a porous medium for thermal energy transfer. I have attached the mathematical model I am trying to follow as well as my current code. I am stuck on how to add the source term Sl, currently it crashes each time I try to run it.\"\"<\/p>\n

#define<\/span> UDM_RHO_F_PREV <\/span>0<\/span>  <\/span>\/\/ UDM index for storing previous rho_f<\/span><\/p>\n

#define<\/span> UDM_LAMBDA_PREV <\/span>1<\/span>  <\/span>\/\/ UDM index for storing previous lambda<\/span><\/p>\n

 <\/p>\n

DEFINE_EXECUTE_ON_LOADING<\/span>(init_values, udf_name)<\/span><\/p>\n

{<\/span><\/p>\n

    <\/span>Thread <\/span>*<\/span>t;<\/span><\/p>\n

    <\/span><\/span>cell_t<\/span> c;<\/span><\/p>\n

    <\/span>Domain <\/span>*<\/span>d <\/span>= <\/span>Get_Domain<\/span>(<\/span>1<\/span>);<\/span> \/\/ Get domain using Fluent API, assuming single-phase flow<\/span><\/p>\n

    <\/span><\/span><\/p>\n

    <\/span>\/* Loop over all cells to initialize UDM values *\/<\/span><\/p>\n

    <\/span><\/span>thread_loop_c<\/span>(t, d)<\/span><\/p>\n

    <\/span>{<\/span><\/p>\n

        <\/span><\/span>begin_c_loop_all<\/span>(c, t)<\/span><\/p>\n

        <\/span>{<\/span><\/p>\n

            <\/span><\/span>C_UDMI<\/span>(c,t,UDM_RHO_F_PREV) <\/span>= <\/span>1000.0<\/span>;<\/span>  <\/span>\/\/initializing previous rho_f<\/span><\/p>\n

            <\/span><\/span>C_UDMI<\/span>(c,t,UDM_LAMBDA_PREV) <\/span>= <\/span>0.0<\/span>;<\/span>  <\/span>\/\/initializing previous lambda<\/span><\/p>\n

        <\/span>}<\/span><\/p>\n

        <\/span><\/span>end_c_loop_all<\/span>(c, t)<\/span><\/p>\n

    <\/span>}<\/span><\/p>\n

}<\/span><\/p>\n

 <\/p>\n

DEFINE_SOURCE<\/span>(energy_sourceN, c, t, dS, eqn)<\/span><\/p>\n

{<\/span><\/p>\n

  <\/span>real lambda, lambda_prev, <\/span>V<\/span>[ND_ND], rho_f, Sl, d_lambda_dt, grad_lambda_dot_V, T, rho_f_prev;<\/span><\/p>\n

  <\/span><\/span><\/p>\n

  <\/span>T <\/span>= <\/span>C_T<\/span>(c, t);<\/span><\/p>\n

  <\/span>rho_f <\/span>= <\/span>C_R<\/span>(c, t);<\/span><\/p>\n

  <\/span><\/span>C_CENTROID<\/span>(V, c, t);<\/span><\/p>\n

  <\/span><\/span><\/p>\n

  <\/span>rho_f_prev <\/span>= <\/span>C_UDMI<\/span>(c, t, UDM_RHO_F_PREV);<\/span>  <\/span>\/\/ Fetch the previous value of rho_f from UDM<\/span><\/p>\n

  <\/span>lambda_prev <\/span>= <\/span>C_UDMI<\/span>(c, t, UDM_LAMBDA_PREV);<\/span>  <\/span>\/\/ Fetch the previous value of lambda from UDM<\/span><\/p>\n

 <\/p>\n

  <\/span><\/span>\/\/ Calculate lambda<\/span><\/p>\n

  <\/span><\/span>if<\/span> (T <\/span><<\/span> Tsolidus)<\/span><\/p>\n

    <\/span>lambda <\/span>= <\/span>0.0<\/span>;<\/span><\/p>\n

  <\/span><\/span>else if<\/span> (T <\/span>><\/span> Tliquidus)<\/span><\/p>\n

    <\/span>lambda <\/span>= <\/span>1.0<\/span>;<\/span><\/p>\n

  <\/span><\/span>else<\/span><\/p>\n

    <\/span>lambda <\/span>=<\/span> (T <\/span>–<\/span> Tsolidus) <\/span>\/<\/span> (Tliquidus <\/span>–<\/span> Tsolidus);<\/span><\/p>\n

 <\/p>\n

  <\/span><\/span>\/\/ Calculate d(lambda*rho_f*L_f)\/dt<\/span><\/p>\n

  <\/span>d_lambda_dt <\/span>=<\/span> ((rho_f <\/span>*<\/span> lambda <\/span>*<\/span> L_f <\/span>* <\/span>0.85<\/span>) <\/span>–<\/span> (rho_f_prev <\/span>*<\/span> lambda_prev <\/span>*<\/span> L_f <\/span>* <\/span>0.85<\/span>)) <\/span>\/<\/span> CURRENT_TIMESTEP;<\/span><\/p>\n

 <\/p>\n

  <\/span><\/span>\/\/ The gradient calculation requires more attention. Below is just a placeholder, and you need to implement the correct gradient calculation.<\/span><\/p>\n

  <\/span>grad_lambda_dot_V <\/span>=<\/span> (<\/span>C_R_G<\/span>(c,t)[<\/span>0<\/span>] <\/span>* <\/span>V<\/span>[<\/span>0<\/span>] <\/span>+ <\/span>C_R_G<\/span>(c,t)[<\/span>1<\/span>] <\/span>* <\/span>V<\/span>[<\/span>1<\/span>]) <\/span>*<\/span> lambda <\/span>*<\/span> L_f;<\/span><\/p>\n

 <\/p>\n

  <\/span>Sl <\/span>=<\/span> d_lambda_dt <\/span>+<\/span> grad_lambda_dot_V;<\/span><\/p>\n

 <\/p>\n

  <\/span><\/span>dS<\/span>[eqn] <\/span>= <\/span>0<\/span>;<\/span> \/\/ Adjust the source term linearization if necessary<\/span><\/p>\n

 <\/p>\n

  <\/span><\/span>\/\/ Store the current time step values of rho_f and lambda to UDM<\/span><\/p>\n

  <\/span><\/span>C_UDMI<\/span>(c, t, UDM_RHO_F_PREV) <\/span>=<\/span> rho_f;<\/span><\/p>\n

  <\/span><\/span>C_UDMI<\/span>(c, t, UDM_LAMBDA_PREV) <\/span>=<\/span> lambda;<\/span><\/p>\n

 <\/p>\n

  <\/span><\/span>return<\/span> Sl;<\/span><\/p>\n

}<\/span><\/p>\n

 <\/p>\n","protected":false},"template":"","class_list":["post-311895","topic","type-topic","status-closed","hentry","topic-tag-energy-source-term-2","topic-tag-fluent","topic-tag-porosity-1","topic-tag-porous","topic-tag-udf"],"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