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    请问一下各位大佬,欧拉-欧拉气固两相流模拟,设置流体域旋转后,wall可以设置成不旋转吗,对结果有没有影响,因为wall设置成旋转之后,就无法设置镜面反射系数了

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    各位CFD大佬,小弟最近在用fluent做模拟时遇到一个问题,物理背景就是管内的热水以射流的方式喷出然后被周围的环境冷水稀释,在做小模型模拟(x=40m y=2m z=13.3cm)的时候,模拟结果尚可,对称性很完美,但在做大模型的时候(x=4000m y=2000m z=10m),模拟结果很不好。
    用的稳态模拟,大模型网格数量大概七百多万,用的reliazable k-e湍流模型,进口的湍流参数设置用CFD计算器估算过了,另外在模拟的时候fluent一直有湍流粘度比超限的提示,但小模型就不会有,不知道最后的不对称结果和这个是不是有关系。
    1564dc71-8ed2-4905-ba1b-67fbca1936e3-图片.png
    热水从圆的四周均匀喷射出来,然后被流动的冷水稀释,冷水流动方向从左至右,可以看到图中并没有达到一个对称效果,等值线都没有对称。
    21f863e0-2b3c-4e9f-994a-ae3797889acf-图片.png
    热水进口在上图的最底部,垂直向上喷射,中间比较黑的那一块有一块顶盖,作用是让热水向周围扩散开来而不是垂直向上冲,图中看到网格有些瑕疵的地方是tecplot的显示问题,可以忽略。
    a652dbd8-6ce0-4c30-9c4a-97e6fee8e965-892fea64760b5fcdfe9299ba371783e.png
    从这张图可以看出热水向上喷射,被顶盖挡住,最后向四周扩散上浮的过程。

    总结一下几点疑问:
    1.模拟时fluent的湍流粘度比超限警告是否和最后模拟结果的不对称有关系?
    2.小模型模拟结果对称,而大模型就不行,和网格的大小有关系吗?小模型的最大网格大概也就在厘米级别,而大模型的最大网格一般在米级别(最大有五米左右)。
    其实最核心的诉求还是想解决对称性的问题,最好不要用对称边界条件,能用整个模型就用整个模型。

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    采用overset重叠网格和UDF函数模拟串列三圆柱的涡激振动,其中UDF分别尝试了Newmark-Beta方法和4阶Runge Kutta法获取圆柱的振动响应,通过DEFINE_CG_MOTION宏赋予三个圆柱及component cells的运动速度,算例的雷诺数约200,采用k-omega sst模型,考虑水作为来流介质,计算过程中尝试了时间步长从1.0e-3缩小到1.0e-5等多个量级,但是求解过程总是出现升力和升力矩突然骤增,继而导致圆柱运动速度过大,最终计算发散。

    请各位大佬帮忙看看是哪里出问题?

    具体的UDF和部分设置如下:

    #include "udf.h" #include "sg_mem.h" #include "dynamesh_tools.h" #define PI 3.141592654 #define zoneID_1 4 #define zoneID_2 16 #define zoneID_3 20 FILE *outNB,*outRK; static real y = 0.0; static real yRK = 0.0; static real dy = 0.0; static real vy = 0.0; static real vyRK = 0.0; static real vyRK2 = 0.0; static real ay = 0.0; static real current_time = 5; static real y2 = 0.0; static real y2RK = 0.0; static real dy2 = 0.0; static real vy2 = 0.0; static real vy2RK = 0.0; static real vy2RK2 = 0.0; static real ay2 = 0.0; static real current_time2 = 5; static real y3 = 0.0; static real y3RK = 0.0; static real dy3 = 0.0; static real vy3 = 0.0; static real vy3RK = 0.0; static real vy3RK2 = 0.0; static real ay3 = 0.0; static real current_time3 = 5; DEFINE_CG_MOTION(cylinder_1,dt,vel,omega,time,dtime) { real ctime = RP_Get_Real("flow-time"); real ctimestep = RP_Get_Integer("time-step"); real niter = N_ITER; if (current_time < ctimestep) { current_time = ctimestep; /*Define variables*/ /*Mesh variables*/ real cg[3],vcg[3]; /*Cylinder variables*/ real diameter = 0.063; real fn = 1.0892; real density = 998.2; real length = 1; real water_depth = 1; real mass_ratio = 0.3937; real damping_ratio = 0.01; real mass = mass_ratio*density*pow((0.5*diameter),2)*PI*length; real ad_mass = mass*(0); /*density*pow((0.5*diameter),2)*PI*water_depth;*/ real total_mass = mass + ad_mass; real k = 4*pow((PI*fn),2)*total_mass; real c = 2 * damping_ratio * sqrt(k*total_mass); /*Force calculation. Force = F_pressure + F_viscous*/ real fy = 0.0; real fvy = 0.0; int i; #if !RP_HOST Thread *tc,*thread; Domain *d = Get_Domain(1); face_t f; tc = Lookup_Thread(d,zoneID_1); thread = DT_THREAD(dt); NV_S(vel, =, 0.0); NV_S(omega, =, 0.0); real NV_VEC(A); begin_f_loop(f,tc) { if (PRINCIPAL_FACE_P(f,tc)) { fvy = F_STORAGE_R_N3V(f,tc,SV_WALL_SHEAR)[1]*-1; /*“*-1”表示方向*/ F_AREA(A,f,tc); /*Force calculation with a depth of 1m*/ fy += F_P(f,tc)*A[1] + fvy; } } end_f_loop(f,tc) #endif #if RP_NODE fy = PRF_GRSUM1(fy); #endif /*Dynamic mesh position*/ #if!RP_HOST for (i=0;i<3;i++) { cg[i]=DT_CG(dt)[i]; vcg[i] = DT_VEL_CG(dt)[i]; } Message("Position CG: %f \n",cg[1]); #endif node_to_host_real_2(fy,cg[1]); /*Numerical methods*/ /*Numark-beta*/ real beta = 0.25; real gamma = 0.5; real term0 = (1/(beta*dtime*dtime))*(mass+ad_mass) + (gamma/(beta*dtime))*c; real term1 = (1/(beta*dtime))*(mass+ad_mass) + ((gamma/beta)-1)*c; real term2 = ((1/(2*beta))-1)*(mass+ad_mass) + dtime*((gamma/(2*beta))-1)*c; real Keff = k + term0; real Reff = fy*water_depth + term0*cg[1] + term1*vy + term2*ay; Message("Velocity: %f \n",vy); dy = Reff/Keff - cg[1]; y += dy; real vprev = vy; vy = (gamma/(beta*dtime))*dy + (1-(gamma/beta))*vy + dtime*(1-(gamma/(2*beta)))*ay; ay = (1/(beta*dtime*dtime))*dy - (1/(beta*dtime))*vprev - ((1/(2*beta))-1)*ay; /*Runge-kutta 4th order*/ real K1 = (fy*water_depth - c*vyRK - k*yRK) / total_mass; real K2 = (fy*water_depth - c*(vyRK+dtime*0.5*K1) - k*(yRK+dtime*0.5*vyRK)) / total_mass; real K3 = (fy*water_depth - c*(vyRK+dtime*0.5*K2) - k*(yRK+dtime*0.5*vyRK+dtime*dtime*K1/4)) / total_mass; real K4 = (fy*water_depth - c*(vyRK+dtime*K3) - k*(yRK+dtime*vyRK+dtime*dtime*K1/2)) / total_mass; yRK = yRK + vyRK*dtime + dtime*dtime*(K1 + K2 + K3 + K4)/6; vyRK = vyRK + dtime*(K1 + K2 + K3 + K4)/6; /*Transfer result to the dynamic mesh*/ vel[0] = 0.0; vel[1] = vyRK; /*Save files*/ #if !RP_NODE /*Message ("Force = %f, pos = %f, vel = %f, acc = %f\n", fy, cg[1], y, vy);*/ if(NULL == (outNB = fopen("dataNB1.txt","a"))) { Error("Could not open file for append!\n"); } fprintf(outNB,"%16.4e %12.1f %16.3e %16.7f %16.7f %16.7f \n", ctime,niter, fy , cg[1], y, vy); fclose(outNB); if(NULL == (outRK = fopen("dataRK1.txt","a"))) { Error("Could not open file for append!\n"); } fprintf(outRK,"%16.4e %12.1f %16.3e %16.7f %16.7f %16.7f \n", ctime,niter, fy , cg[1], yRK, vyRK); fclose(outRK); #endif } /*Transfer result to the dynamic mesh*/ vel[0] = 0.0; vel[1] = vyRK; } DEFINE_CG_MOTION(cylinder_1_frontgrid_1,dt,vel,omega,time,dtime) { NV_S(vel, =, 0.0); NV_S(omega, =, 0.0); vel[0]=0.0; vel[1]=vyRK; } DEFINE_CG_MOTION(cylinder_1_overset_2,dt,vel,omega,time,dtime) { NV_S(vel, =, 0.0); NV_S(omega, =, 0.0); vel[0]=0.0; vel[1]=vyRK; } DEFINE_ZONE_MOTION(cylinder_1_zone,omega,axis,origin,velocity,time,dtime) { N3V_D(velocity, =, 0, 0, 0); N3V_S(origin, =, -0.32); N3V_D(axis, =, 0.0, 0.0, 1.0); velocity[1]=vyRK; } DEFINE_CG_MOTION(cylinder_2,dt,vel,omega,time,dtime) { real ctime = RP_Get_Real("flow-time"); real ctimestep = RP_Get_Integer("time-step"); real niter = N_ITER; if (current_time2 < ctimestep) { current_time2 = ctimestep; /*Define variables*/ /*Mesh variables*/ real cg[3],vcg[3]; /*Cylinder variables*/ real diameter = 0.063; real fn = 1.0892; real density = 998.2; real length = 1; real water_depth = 1; real mass_ratio = 0.3937; real damping_ratio = 0.01; real mass = mass_ratio*density*pow((0.5*diameter),2)*PI*length; real ad_mass = mass*(0); /*density*pow((0.5*diameter),2)*PI*water_depth;*/ real total_mass = mass + ad_mass; real k = 4*pow((PI*fn),2)*total_mass; real c = 2 * damping_ratio * sqrt(k*total_mass); /*Force calculation. Force = F_pressure + F_viscous*/ real fy = 0.0; real fvy = 0.0; int i; #if !RP_HOST Thread *tc,*thread; Domain *d = Get_Domain(1); face_t f; tc = Lookup_Thread(d,zoneID_2); thread = DT_THREAD(dt); NV_S(vel, =, 0.0); NV_S(omega, =, 0.0); real NV_VEC(A); begin_f_loop(f,tc) { if (PRINCIPAL_FACE_P(f,tc)) { fvy = F_STORAGE_R_N3V(f,tc,SV_WALL_SHEAR)[1]*-1; /*“*-1”表示方向*/ F_AREA(A,f,tc); /*Force calculation with a depth of 1m*/ fy += F_P(f,tc)*A[1] + fvy; } } end_f_loop(f,tc) #endif #if RP_NODE fy = PRF_GRSUM1(fy); #endif /*Dynamic mesh position*/ #if!RP_HOST for (i=0;i<3;i++) { cg[i]=DT_CG(dt)[i]; vcg[i] = DT_VEL_CG(dt)[i]; } Message("Position CG: %f \n",cg[1]); #endif node_to_host_real_2(fy,cg[1]); /*Numerical methods*/ /*Numark-beta*/ real beta = 0.25; real gamma = 0.5; real term0 = (1/(beta*dtime*dtime))*(mass+ad_mass) + (gamma/(beta*dtime))*c; real term1 = (1/(beta*dtime))*(mass+ad_mass) + ((gamma/beta)-1)*c; real term2 = ((1/(2*beta))-1)*(mass+ad_mass) + dtime*((gamma/(2*beta))-1)*c; real Keff = k + term0; real Reff = fy*water_depth + term0*cg[1] + term1*vy2 + term2*ay2; Message("Velocity: %f \n",vy2); dy2 = Reff/Keff - cg[1]; y2 += dy2; real vprev = vy2; vy2 = (gamma/(beta*dtime))*dy2 + (1-(gamma/beta))*vy2 + dtime*(1-(gamma/(2*beta)))*ay2; ay2 = (1/(beta*dtime*dtime))*dy2 - (1/(beta*dtime))*vprev - ((1/(2*beta))-1)*ay2; /*Runge-kutta 4th order*/ real K1 = (fy*water_depth - c*vy2RK - k*yRK) / total_mass; real K2 = (fy*water_depth - c*(vy2RK+dtime*0.5*K1) - k*(y2RK+dtime*0.5*vy2RK)) / total_mass; real K3 = (fy*water_depth - c*(vy2RK+dtime*0.5*K2) - k*(y2RK+dtime*0.5*vy2RK+dtime*dtime*K1/4)) / total_mass; real K4 = (fy*water_depth - c*(vy2RK+dtime*K3) - k*(y2RK+dtime*vy2RK+dtime*dtime*K1/2)) / total_mass; y2RK = y2RK + vy2RK*dtime + dtime*dtime*(K1 + K2 + K3 + K4)/6; vy2RK = vy2RK + dtime*(K1 + K2 + K3 + K4)/6; /*Transfer result to the dynamic mesh*/ vel[0] = 0.0; vel[1] = vy2RK; /*Save files*/ #if !RP_NODE /*Message ("Force = %f, pos = %f, vel = %f, acc = %f\n", fy, cg[1], y, vy);*/ if(NULL == (outNB = fopen("dataNB2.txt","a"))) { Error("Could not open file for append!\n"); } fprintf(outNB,"%16.4e %12.1f %16.3e %16.7f %16.7f %16.7f \n", ctime,niter, fy , cg[1], y2, vy2); fclose(outNB); if(NULL == (outRK = fopen("dataRK2.txt","a"))) { Error("Could not open file for append!\n"); } fprintf(outRK,"%16.4e %12.1f %16.3e %16.7f %16.7f %16.7f \n", ctime,niter, fy , cg[1], y2RK, vy2RK); fclose(outRK); #endif } /*Transfer result to the dynamic mesh*/ vel[0] = 0.0; vel[1] = vy2RK; } DEFINE_CG_MOTION(cylinder_2_frontgrid_1,dt,vel,omega,time,dtime) { NV_S(vel, =, 0.0); NV_S(omega, =, 0.0); vel[0]=0.0; vel[1]=vy2RK; } DEFINE_CG_MOTION(cylinder_2_overset_2,dt,vel,omega,time,dtime) { NV_S(vel, =, 0.0); NV_S(omega, =, 0.0); vel[0]=0.0; vel[1]=vy2RK; } DEFINE_ZONE_MOTION(cylinder_2_zone,omega,axis,origin,velocity,time,dtime) { N3V_D(velocity, =, 0, 0, 0); N3V_S(origin, =, 0.0); N3V_D(axis, =, 0.0, 0.0, 1.0); velocity[1]=vy2RK; } DEFINE_CG_MOTION(cylinder_3,dt,vel,omega,time,dtime) { real ctime = RP_Get_Real("flow-time"); real ctimestep = RP_Get_Integer("time-step"); real niter = N_ITER; if (current_time3 < ctimestep) { current_time3 = ctimestep; /*Define variables*/ /*Mesh variables*/ real cg[3],vcg[3]; /*Cylinder variables*/ real diameter = 0.063; real fn = 1.0892; real density = 998.2; real length = 1; real water_depth = 1; real mass_ratio = 0.3937; real damping_ratio = 0.01; real mass = mass_ratio*density*pow((0.5*diameter),2)*PI*length; real ad_mass = mass*(0); /*density*pow((0.5*diameter),2)*PI*water_depth;*/ real total_mass = mass + ad_mass; real k = 4*pow((PI*fn),2)*total_mass; real c = 2 * damping_ratio * sqrt(k*total_mass); /*Force calculation. Force = F_pressure + F_viscous*/ real fy = 0.0; real fvy = 0.0; int i; #if !RP_HOST Thread *tc,*thread; Domain *d = Get_Domain(1); face_t f; tc = Lookup_Thread(d,zoneID_3); thread = DT_THREAD(dt); NV_S(vel, =, 0.0); NV_S(omega, =, 0.0); real NV_VEC(A); begin_f_loop(f,tc) { if (PRINCIPAL_FACE_P(f,tc)) { fvy = F_STORAGE_R_N3V(f,tc,SV_WALL_SHEAR)[1]*-1; /*“*-1”表示方向*/ F_AREA(A,f,tc); /*Force calculation with a depth of 1m*/ fy += F_P(f,tc)*A[1] + fvy; } } end_f_loop(f,tc) #endif #if RP_NODE fy = PRF_GRSUM1(fy); #endif /*Dynamic mesh position*/ #if!RP_HOST for (i=0;i<3;i++) { cg[i]=DT_CG(dt)[i]; vcg[i] = DT_VEL_CG(dt)[i]; } Message("Position CG: %f \n",cg[1]); #endif node_to_host_real_2(fy,cg[1]); /*Numerical methods*/ /*Numark-beta*/ real beta = 0.25; real gamma = 0.5; real term0 = (1/(beta*dtime*dtime))*(mass+ad_mass) + (gamma/(beta*dtime))*c; real term1 = (1/(beta*dtime))*(mass+ad_mass) + ((gamma/beta)-1)*c; real term2 = ((1/(2*beta))-1)*(mass+ad_mass) + dtime*((gamma/(2*beta))-1)*c; real Keff = k + term0; real Reff = fy*water_depth + term0*cg[1] + term1*vy3 + term2*ay3; Message("Velocity: %f \n",vy3); dy3 = Reff/Keff - cg[1]; y3 += dy3; real vprev = vy3; vy3 = (gamma/(beta*dtime))*dy3 + (1-(gamma/beta))*vy3 + dtime*(1-(gamma/(2*beta)))*ay3; ay3 = (1/(beta*dtime*dtime))*dy3 - (1/(beta*dtime))*vprev - ((1/(2*beta))-1)*ay3; /*Runge-kutta 4th order*/ real K1 = (fy*water_depth - c*vy3RK - k*y3RK) / total_mass; real K2 = (fy*water_depth - c*(vy3RK+dtime*0.5*K1) - k*(y3RK+dtime*0.5*vy3RK)) / total_mass; real K3 = (fy*water_depth - c*(vy3RK+dtime*0.5*K2) - k*(y3RK+dtime*0.5*vy3RK+dtime*dtime*K1/4)) / total_mass; real K4 = (fy*water_depth - c*(vy3RK+dtime*K3) - k*(y3RK+dtime*vy3RK+dtime*dtime*K1/2)) / total_mass; y3RK = y3RK + vy3RK*dtime + dtime*dtime*(K1 + K2 + K3 + K4)/6; vy3RK = vy3RK + dtime*(K1 + K2 + K3 + K4)/6; /*Transfer result to the dynamic mesh*/ vel[0] = 0.0; vel[1] = vy3RK; /*Save files*/ #if !RP_NODE /*Message ("Force = %f, pos = %f, vel = %f, acc = %f\n", fy, cg[1], y, vy);*/ if(NULL == (outNB = fopen("dataNB3.txt","a"))) { Error("Could not open file for append!\n"); } fprintf(outNB,"%16.4e %12.1f %16.3e %16.7f %16.7f %16.7f \n", ctime,niter, fy , cg[1], y3, vy3); fclose(outNB); if(NULL == (outRK = fopen("dataRK3.txt","a"))) { Error("Could not open file for append!\n"); } fprintf(outRK,"%16.4e %12.1f %16.3e %16.7f %16.7f %16.7f \n", ctime,niter, fy , cg[1], y3RK, vy3RK); fclose(outRK); #endif } /*Transfer result to the dynamic mesh*/ vel[0] = 0.0; vel[1] = vy3RK; } DEFINE_CG_MOTION(cylinder_3_frontgrid_1,dt,vel,omega,time,dtime) { NV_S(vel, =, 0.0); NV_S(omega, =, 0.0); vel[0]=0.0; vel[1]=vy3RK; } DEFINE_CG_MOTION(cylinder_3_overset_2,dt,vel,omega,time,dtime) { NV_S(vel, =, 0.0); NV_S(omega, =, 0.0); vel[0]=0.0; vel[1]=vy3RK; } DEFINE_ZONE_MOTION(cylinder_3_zone,omega,axis,origin,velocity,time,dtime) { N3V_D(velocity, =, 0, 0, 0); N3V_S(origin, =, 0.32); N3V_D(axis, =, 0.0, 0.0, 1.0); velocity[1]=vy3RK; }

    运动速度.png
    运动速度

    运动位移.png
    运动位移

    压力系数.png
    压力系数

    动网格设置.png
    动网格设置

  • 流向周期性能量不守恒

    Fluent
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    C

    各位大佬好,模型是一个0.125x0.5x0.6m的光滑通道,上下壁面均为无滑移的300K恒温壁面,进口温度320K,进出口及左右壁面均采用周期性边界条件,模拟步骤是先用RANS模拟,之后使用TUI指令添加扰动然后切换到LES模拟。按理说流体温度应该小于等于320K而且随时间逐渐减小,但是云图画出来最高温度有323K,又模拟了0.5s后最高温度没什么变化其他地方的温度似乎也没什么变化。周期性设置如图(压力梯度最开始为0)搜狗截图20230903172308.png
    我想知道是为啥 :136:

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    2

    我采用的稳态MRF模型进行模拟,如果桨距角改变,同一来流速度下给旋转域设置的旋转速度需要改变吗

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    B

    81a56a41-f2c6-4e5c-8504-2cb7df0a1f28-image.png ,我看帮助文档中DPM对droplet的描述是换热、蒸发和沸腾,这都是液滴材料从液相传质到气相,请问能不能实现从气相到液相的传质(就是吸收)?

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    320 浏览
    B

    81a56a41-f2c6-4e5c-8504-2cb7df0a1f28-image.png ,我看帮助文档中DPM对droplet的描述是换热、蒸发和沸腾,这都是液滴材料从液相传质到气相,请问能不能实现从气相到液相的传质(就是吸收)?

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    小白初学fluent,对凝固过程有了解,也做过连铸凝固模型案例,但是组分输送模型和多相流VOF要怎么开启还不清楚,有没有大神教一下怎么设置

  • dpm模型模拟闪蒸

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    请问一下各位大佬,在使用dpm模拟液滴闪蒸时,液滴沸点设置为373k,液滴温度设置为400k,连续相温度为300k,连续相介质为空气,采用双向耦合进行计算,当液滴颗粒射入连续相中时,连续相喷嘴处的温度就迅速上升,可达上千度,甚至报温度超限的错误,请问一下这是为什么呀![QQ图片20230818084454.jpg

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    C

    个人觉得这个功能特别实用,特别是对于边界很多的案例,能直观看到边界在哪个位置。但是2020以后的版本都没有找到此功能,想问一下是阉割掉了还是被别的功能替代了?谢谢!微信图片_20230818185948.png

  • 使用UDS的时候怎么确定单位啊?

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    使用UDS计算电势和流体所受到的电场力,但是在边界定义标量数值的时候默认单位是1吗?怎么弄成电势单位?

  • 关于PBM模型的聚合核UDF问题

    Fluent
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    欧拉欧拉模型的群体平衡方程,如果有多相参与计算那么聚合核的UDF需要额外改吗?比如气固的聚合核UDF在气固固能直接用吗? 因为我使用的FLUENT的DQMOM模型,里面必须有三相参与计算,需要编聚合核的UDF。

  • 利用Tosca Fluid做流道优化

    Fluent
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    K

    打扰大家,有用Tosca Fluid做流道优化的吗,或者用别的软件也行,加个好友,一起讨论学习。

  • 五一了,送李老师一份礼物,请笑纳

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    waltenW

    2023-04-27_113417.png

    东岳,记录美好算法
    :146:

  • dpm求助

    Fluent
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    C

    我用fluent中dpm模型做壁面磨损,想请问一下颗粒的固相体积分数是用混合模型设定的还是需要自己计算,若需要自己计算应该怎么计算,还有里面的颗粒质量流率怎么计算,可以解答一下或者提供相关文献吗?

  • 0 赞同
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    365 浏览
    E

    大家好,
    问题描述
    如图1所示,整个流体域由fluid_1, fluid_2和fluid_3组成,它们之间通过interface连接,其中面wall_bot_f1、流体域fluid_2以及流体域fluid_3以相同速度向右移动,我使用”DEFINE_CG_MOTION”控制wall_bot_f1的运动,而对于流体域fluid_2和fluid_3则使用“DEFINE_ZONE_MOTION”,在fluent运行过程中,出现了警告:Warning: incompatible interaction between moving mesh and dynamic mesh model detected!
    请问为何会出现警告提示,该如何解决?感谢~
    Interface设置:
    Interface_1:wall_bot_f1与wall_top_f2组成
    interface_2:wall_bot_f2与wall_top_f3组成
    动网格设置(图2)
    Deforming: wall_f1
    Rigid body: wall bot_f1;
    Rigid body: Interface_1;
    Rigid body: Interface_1-non-overlapping;
    0e8be7a5-ffac-4e43-b541-7449fa25b17a-image.png
    图1
    1598c895-e13d-4581-b913-ec1573299d2a-image.png
    图2

  • Opening边界,预期的出口变为入口

    Fluent
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    Y

    在Ansys CFX中使用速度入口,opening压力出口计算单一入口双出口问题,发现由于两个出口的面积相差较悬殊,面积较小的出口算着算着就成为入口了,一开始入口流量等于两个出口流量之后。回流之后变成入口和面积较小的出口的流量之和等于面积较大的出口流量。这种情况应该如何解决呢?可以通过延长出口来减少回流么?
    图中蓝线为入口流量,红色和绿色为出口流量*-1 第一周期后修改了边界条件,绿色的直接变成入口了
    a990604e-91a5-40d6-b833-d1957916216a-image.png

  • 关于fluent 的interpolate的一个问题

    Fluent
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    在进行网格无关性验证时,通过在不同网格尺度间的插值操作,可以显著的节约计算时间。问题是,在fluent的框架下,插值操作应该是从粗网格到细网格, 还是细网格到粗网格?
    (i) 貌似, 好像, 似乎粗网格到细网格的效果好像更好。
    (2) fluent在help里面也只提到了interpolate 是zeroth-order。有没有人能具体的解释一下interpolate的原理。

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    Z

    使用transient profile定义动网格移动速度,内容如下:
    profile-v 2 14 0
    time inlet-v
    0 0
    300 0
    310 1.538E-4
    9790 1.538E-4
    9800 1.667E-4
    9910 1.667E-4
    9920 9.524E-5
    10330 9.524E-5
    ......
    File-Read-Profile读入,然后显示
    “Reading transient profile file...
    14 "profile-v" transient-profile points time, inlet-v,.”

    但是,动网格条件设置完后,开始Display Zone Motion,显示
    “Warning: Can't identify any field of profile profile-v.
    No motion specified.
    ......”

    参照https://www.topcfd.cn/883/尝试了csv,表格等,但是都有warning。
    有没有哪位遇到过相同问题,请问那个地方出错,要如何解决?

  • 亚临界流体的物性分段设置后发散

    Fluent
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    F

    计算亚临界水在圆管中的流动和传热,压力为20MPa,流体入口温度300k,管壁623k,想计算二维稳态下的管内的温度分布,用水的常物性参数很快就收敛了,但是分段插值改成变物性后就收敛不了,请教下是什么原因?
    1.jpg