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Monkeystar

新虫 (初入文坛)

应助: 0 (幼儿园)
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虫号: 8410502
注册: 2018-03-30
专业: 工程热力学

[求助] 求大神仅仅是解释一下fluent帮助文件中的这个udf

int、real这些是定义数据类型我知道，Nu是努塞尔数，Sc是施密特数这些我也知道，
主要是：1、加粗的部分不懂。2、有箭头的东西不太懂，如c->yi[ns]，这个c到底是什么，怎么可以弄出yi、密度这些东西。3、cvap_surf[ns]是什么、gas_index又是什么，气体指数？具体是指哪个物理量

udf如下（帮助文件udf篇中的2.5.5.3处）：

#include "udf.h"
DEFINE_DPM_HEAT_MASS(multivap,p,Cp,hgas,hvap,cvap_surf,Z,dydt,dzdt)
{
int ns;
Material *sp;
real dens_total = 0.0;    /* total vapor density*/
real P_total = 0.0;    /* vapor pressure */
int nc = TP_N_COMPONENTS(p); /* number of particle components */
Thread *t0 = P_CELL_THREAD(p); /* thread where the particle is in*/
Material *gas_mix = THREAD_MATERIAL(DPM_THREAD(t0, p)); /* gas mixture material */
Material *cond_mix = P_MATERIAL(p); /* particle mixture material*/
cphase_state_t *c = &(p->cphase); /* cell information of particle location*/
real molwt[MAX_SPE_EQNS]; /* molecular weight of gas species */
real Tp = P_T(p); /* particle temperature */
real mp = P_MASS(p); /* particle mass */
real molwt_bulk = 0.;  /* average molecular weight in bulk gas */
real Dp = DPM_DIAM_FROM_VOL(mp / P_RHO(p)); /* particle diameter */
real Ap = DPM_AREA(Dp);    /* particle surface */
real T,Dso2_l,kso2_l,Dso2_g,Sc,kso2_g,Dca,Kso2_G,tp,Cca,Hso2,Cso2_i,a,e,b;
real Pr =c->sHeat * c->mu / c->tCond; /* Prandtl number */
real Nu = 2.0 + 0.6 * sqrt(p->Re) * pow(Pr, 1./3.); /* Nusselt number */
real h = Nu * c->tCond / Dp;    /* Heat transfer coefficient*/
real dh_dt = h * (c->temp - Tp) * Ap;  /* heat source term*/
dydt[0] += dh_dt / (mp * Cp);
dzdt->energy -= dh_dt;
mixture_species_loop(gas_mix,sp,ns)
{
   molwt[ns] = MATERIAL_PROP(sp,PROP_mwi); /* molecular weight of gas species */
molwt_bulk += c->yi[ns] / molwt[ns]; /* average molecular weight */
}

/* prevent division by zero */
molwt_bulk = MAX(molwt_bulk,DPM_SMALL);

for (ns = 0; ns < nc; ns++)
{
   int gas_index = TP_COMPONENT_INDEX_I(p,ns);  /* gas species index of
   vaporization */
  if(gas_index >= 0)
{
   /* condensed material */
   Material * cond_c = MIXTURE_COMPONENT(cond_mix, ns);
   /* vaporization temperature */
   real vap_temp = MATERIAL_PROP(cond_c,PROP_vap_temp);
   /* diffusion coefficient */
   real D = DPM_BINARY_DIFFUSIVITY(p,cond_c,P_T(p));
   /* Schmidt number */
   real Sc = c->mu / (c->rho * D);
   /* mass transfer coefficient */
   real k = (2. + 0.6 * sqrt(p->Re) * pow(Sc, 1./3.)) * D / Dp;
   /* bulk gas concentration (ideal gas) */
   real cvap_bulk = c->pressure / UNIVERSAL_GAS_CONSTANT / c->temp
   * c->yi[gas_index] / molwt_bulk / solver_par.molWeight[gas_index];
   /* vaporization rate */
   real vap_rate = k * molwt[gas_index] * Ap
   * (cvap_surf[ns] - cvap_bulk);
   /* no vaporization below vaporization temperature, no condensation */
   if (Tp < vap_temp || vap_rate < 0.0)
      vap_rate = 0.;

   dydt[1+ns] -= vap_rate;
   dzdt->species[gas_index] += vap_rate;
   /* dT/dt = dh/dt / (m Cp)*/
   dydt[0] -= hvap[gas_index] * vap_rate / (mp * Cp);
   /* gas enthalpy source term */
   dzdt->energy += hgas[gas_index] * vap_rate;

   P_total += cvap_surf[ns];
   dens_total += cvap_surf[ns] * molwt[gas_index];
   }
}
  /* multicomponent boiling */
P_total *= Z * UNIVERSAL_GAS_CONSTANT * Tp;
if (P_total > c->pressure && dydt[0] > 0.)
   {
      real h_boil = dydt[0] * mp * Cp;
      /* keep particle temperature constant */
      dydt[0] = 0.;
      for (ns = 0; ns < nc; ns++)
      {
         int gas_index = TP_COMPONENT_INDEX_I(p,ns);
         if (gas_index >= 0)
            {
               real boil_rate = h_boil / hvap[gas_index] * cvap_surf[ns] *
                  molwt[gas_index] / dens_total;
               /* particle component mass source term */
               dydt[1+ns] -= boil_rate;
               /* fluid species source */
               dzdt->species[gas_index] += boil_rate;
               /* fluid energy source */
               dzdt->energy += hgas[gas_index] * boil_rate;
            }
      }
   }
}

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