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[求助]
求大神仅仅是解释一下fluent帮助文件中的这个udf
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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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