{"id":301458,"date":"2023-08-15T02:42:49","date_gmt":"2023-08-15T02:42:49","guid":{"rendered":"\/forum\/forums\/topic\/the-udf-of-heat-transfer-coefficient-in-two-fluids-model-eulerian-model\/"},"modified":"2023-08-15T02:42:49","modified_gmt":"2023-08-15T02:42:49","slug":"the-udf-of-heat-transfer-coefficient-in-two-fluids-model-eulerian-model","status":"closed","type":"topic","link":"https:\/\/innovationspace.ansys.com\/forum\/forums\/topic\/the-udf-of-heat-transfer-coefficient-in-two-fluids-model-eulerian-model\/","title":{"rendered":"The UDF of Heat Transfer Coefficient In Two-Fluids Model (Eulerian Model)"},"content":{"rendered":"

Hello everyone, I have a question regarding the usage of a User-Defined Function (UDF) to define the interphase heat transfer coefficient<\/strong> for the Eulerian model (Two-Fluids Model,TFM) within ANSYS FLUENT. I’m wondering whether the UDF should return the heat transfer coefficient ‘h’ (measured in W\/m²K) directly, or if it should return the product of the heat transfer coefficient ‘h’ and the interface area ‘Ai’ (measured in 1\/m). Additionally, I have a few minor questions to ask:<\/p>\n

    \n
  1. \n

    I’ve developed a UDF based on the Ranz-Marshall correlation<\/strong> to compute the interphase heat transfer coefficient between the liquid phase and the interface<\/strong>. However, the computed results differ from those obtained using FLUENT’s internal Ranz-Marshall correlation. I’m seeking insights into the potential reasons for this disparity.<\/p>\n<\/li>\n

  2. \n

    Concerning the correlation itself, should the ‘Pr’ value in the correlation refer to the Prandtl number of the gas phase<\/strong>? I came across this information in the FLUENT Theory Guide, but I’m uncertain about its accuracy.<\/p>\n<\/li>\n

  3. \n

    Here is the UDF code I have written:<\/p>\n<\/li>\n<\/ol>\n

    include “udf.h”
    DEFINE_EXCHANGE_PROPERTY(htc_1, c, mixthread, pi1, pi2)
    {
        Thread* liqthread, * vapthread;
        real Nu, h, h_eff, Re, Pr, vel,d,k,cp,mu,Ai;
        real NV_VEC(v);
        liqthread = THREAD_SUB_THREAD(mixthread, pi1);
        vapthread = THREAD_SUB_THREAD(mixthread, pi2);
        d = C_PHASE_DIAMETER(c, vapthread);
        k = C_K_L(c, vapthread);
        cp = C_CP(c, vapthread);
        mu = C_MU_L(c, vapthread);
        Pr = (cp * mu) \/ k;
        NV_DD(v, =, C_U(c, liqthread), C_V(c, liqthread), C_W(c, liqthread), -, C_U(c, vapthread), C_V(c, vapthread), C_W(c, vapthread));
        vel = NV_MAG(v);
        Re = (C_R(c, liqthread) * vel * d) \/ (C_MU_L(c, liqthread));
        Nu = 2.0 + 0.6 * pow(Re, 0.5) * pow(Pr, 1. \/ 3.);
        h = C_K_L(c, liqthread) * Nu \/ d;
        Ai = 6.0 * C_VOF(c, vapthread) \/ d;
        h_eff = h * Ai;
        return h_eff;
    }<\/h1>\n

    Thanks!?<\/p>\n","protected":false},"template":"","class_list":["post-301458","topic","type-topic","status-closed","hentry","topic-tag-udf"],"aioseo_notices":[],"acf":[],"custom_fields":[{"0":{"_bbp_subscription":["291444","14311"],"_bbp_author_ip":["23.206.193.146"]," _bbp_last_reply_id":["0"]," _bbp_likes_count":["0"],"_btv_view_count":["1651"],"_bbp_topic_status":["unanswered"],"_bbp_status":["publish"],"_bbp_topic_id":["301458"],"_bbp_forum_id":["27792"],"_bbp_engagement":["14311","291444"],"_bbp_voice_count":["2"],"_bbp_reply_count":["4"],"_bbp_last_reply_id":["301695"],"_bbp_last_active_id":["301695"],"_bbp_last_active_time":["2023-08-16 13:02:26"]},"test":"1105808579qq-com"}],"_links":{"self":[{"href":"https:\/\/innovationspace.ansys.com\/forum\/wp-json\/wp\/v2\/topics\/301458","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/innovationspace.ansys.com\/forum\/wp-json\/wp\/v2\/topics"}],"about":[{"href":"https:\/\/innovationspace.ansys.com\/forum\/wp-json\/wp\/v2\/types\/topic"}],"version-history":[{"count":0,"href":"https:\/\/innovationspace.ansys.com\/forum\/wp-json\/wp\/v2\/topics\/301458\/revisions"}],"wp:attachment":[{"href":"https:\/\/innovationspace.ansys.com\/forum\/wp-json\/wp\/v2\/media?parent=301458"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}