CFD中文网

@potatocat 比较的结果如何？可以在fluent中直接设置层流模型吗？

@Cr 十分感谢，问题已经解决了:xinxin:

@cloud1990 在 VOF求解自由水面问题，求解空气区域吗？ 中说：

Image

Left: Correct jet shape predicted by TruVOF technique used in FLOW-3D. Right: Incorrect jet shape predicted by pseudo-VOF technique used by other CFD codes.

Image
Left: FLOW-3D‘s TruVOF technique predicts jet impingement on wall and some outflow. Right: Pseudo-VOF methods don’t predict realistic jetting of fluid on side walls.

从结果上看，flow3D 所谓的TruVOF是有问题的，air velocity 和　air resistance = 0?　这个可能比较适合粗网格计算，作为一个tricky的存在．但理论上，这个TruVOF是无法解决wind wave的问题．

欧拉欧拉那面由于已经在统计学方面已经处理过了，没有噪音。欧拉拉格朗日模拟这面目前有什么文章在处理么？找了找，还没看到。

As an alternative, Lagrangian methods ‘‘discretize” the density function into ‘‘parcels” that are simulated using Monte-Carlo methods. While quite accurate, as in any statistical approach, Lagrangian methods require a relatively large number of parcels to control statistical noise, and thus are computationally expensive.

谢谢各位，解决了:mihu:

@东岳

just for fun:

They used to say if man could fly, he'd have wings. But he did fly. He discovered he had to. Do you wish that the first Apollo mission hadn't reached the moon, or that we hadn't gone on to Mars and then to the nearest star? That's like saying you wish that you still operated with scalpels and sewed your patients up with catgut like your great-great-great-great-grandfather used to. I'm in command. I could order this. But I'm not because, Doctor McCoy is right in pointing out the enormous danger potential in any contact with life and intelligence as fantastically advanced as this. But I must point out that the possibilities, the potential for knowledge and advancement is equally great. Risk. Risk is our business. That's what the CFD is all about. That's why we're aboard her. You may dissent without prejudice. Do I hear a negative vote? (silence around the table) Engineer, solving that imcompressible N.S. equations using PISO algorithm.

@同学博 哈哈 好的

好长，求高手神翻译..

@东岳 :huahua: :huahua: :huahua: :huahua: :huahua: :huahua:

你是不是想把曲面展开为一个平面？https://blog.csdn.net/mrbaolong/article/details/106949340

@东岳 懂了~ 谢谢智慧的李老师~~

@bestucan 先说声谢谢，我去仔细看看

已解决，虚拟机内存调到16g成功安装

之前有点问题，最终如下
\par $C_p$采用4次多项式分段拟合
\begin{equation}\label{equ:NS_Cp}
C_p(T)=a_1+a_2T+a_3T^2+a_4T^3+a_5T^4
\end{equation}
\par静焓
\begin{equation}\label{equ:NS_H}
H(T)=\int_{T_{0}}^{T_{x}}C_p(T)dT=a_1T+\frac{a_2}{2}T^2+\frac{a_3}{3}T^3+\frac{a_4}{4}T^4+\frac{a_5}{5}T^5+a_6
\end{equation}
\par熵
\begin{equation}\label{equ:NS_S}
S(T)=\int_{T_{0}}^{T_{x}}C_p(T)\frac{dT}{T}=a_1\ln{T}+a_2T+\frac{a_3}{2}T^2+\frac{a_4}{3}T^3+\frac{a_5}{4}T^4+a_7
\end{equation}
\par$\bullet$求解静温(已知总温和马赫数)
\begin{equation}\label{equNSUs}
U_s^2=2\left(H(T_{tot})-H(T_{sta})\right)
\end{equation}
\begin{equation}\label{equNSmach}
Mach^2=\frac{U^2}{\gamma(T)R_gT}=\frac{U^2}{\frac{C_p(T)}{C_p(T)-R_g}R_gT}
\end{equation}
\par由(\ref{equ:NSmach})和(\ref{equ:NSUs})得
\begin{equation}\label{equNSTsta}
T_{sta}=\frac{2\left(H(T_{tot})-H(T_{sta})\right)}{Mach^2\frac{C_p(T_{sta})R_g}{C_p(T_{sta})-R_g}}
\end{equation}
$\bullet$求解静压(已知总温、总压和静温)
\par由p等熵过程
\begin{equation}
ds = C_p(T)\frac{dT}{T} -R_g\frac{d p}{p}=0
\end{equation}
\par两边同时积分有
\begin{equation}
\int_{T_{tot}}^{T_{sta}}C_p(T)\frac{dT}{T} =\int_{p_{tot}}^{p_{sta}} R_g\frac{d p}{p}
\end{equation}
\par记
\begin{equation}
S(T_{x})=\int_{T_{0}}^{T_{x}}C_p(T)\frac{dT}{T}
\end{equation}
\par则
\begin{equation}
S(T_{sta}) - S(T_{tot}) = R_g\ln\frac{p_{sta}}{p_{tot}}
\end{equation}
\par那么
\begin{equation}\label{equNS_psta}
p_{sta}=p_{tot}e^{\left(\frac{S(T_{sta})-S(T_{tot})}{R_g}\right)}
\end{equation}

替代文字

@东岳 用的komega湍流模型，有时在outlet处设置了intOut边界，value会设置成0，也尝试过zerogradient，没有value
，0文件夹的omega设置如下：

internalField uniform 53.6; boundaryField { INLET { type turbulentMixingLengthFrequencyInlet; mixingLength 8.52e-4; value uniform 53.6; } OUTLET { type zeroGradient; } BOTWALL { type omegaWallFunction; value $internalField; } UPWALL { type omegaWallFunction; value $internalField; } HEATWALL { type omegaWallFunction; value $internalField; } }

@zhuyuxuan 您好，请问这里“已有的例子只提供了耦合后的icoFoam和simpleFoam求解器”例子是在哪里可以找到？

@Focus 你可能关注我了。点击我ID，出现我的资料页面后，出现我的头像后，在头像右下方点击取消关注

用pisoFoam计算了两百雷诺数的层流圆柱绕流问题。但是计算出来的升阻力系数出现了拍现象，有大神可以指点一下是什么问题吗。以下是升阻力系数图和算例设置求解器.png 离散.png 层流.png U.png P.png Cl.png Cd.png