@vortex 是的 我课题组的代码也是您说的这种 是两部映射法里面中间步用f更新了速度再求压力泊松方程方程再更新最终速度 然而改到openfoam发现出了点小问题:136:

在看《Computational Fluid Dynamics of Dispersed Two-Phase Flows at High Phase Fractions》的时候碰到一个不太理解的地方。
一般的相间动量传递可以写成方程（3.10）
1.png
为了模拟phase inversion， 方程（3.11）加入了b相变成离散相时的曳力、升力等。
但对于方程(3.11)的曳力相，如果仍然是a相为离散相的情况，$\alpha_a$→0 ，$ f_a$→0，
那曳力相前面的部分不就变成$3/4\alpha_a\alpha_b(f_b\frac{C_{db}\rho_a}{d_b})$，和（3.10）里的不一样，b相变成分散相时候应该才是这个形式，虚拟质量力也是一样的情况。 升力也对不上。

2.png

突然想到这个帖子，通过调整边界层厚度可以达到收敛了。

@fangyuanaza
:146:

@李东岳 李老师好，空气密度设为1000的情况流场数据在0.0489范围之内，虽然顶部看起来不好看。
相分数初始场：

#include "../include/initialConditions" defaultFieldValues ( volScalarFieldValue alpha.air 0 volScalarFieldValue alpha.saltwater 1 volScalarFieldValue alpha.water 0 ); regions ( boxToCell { box ($xyz_min 0.1 $xyz_min) ($xyz_max $xyz_max $xyz_max); fieldValues ( volScalarFieldValue alpha.air 1 volScalarFieldValue alpha.saltwater 0 ); } boxToCell { box ($xyz_min 0 $xyz_min) ($xyz_max 0.1 $xyz_max); fieldValues ( volScalarFieldValue alpha.saltwater 0 volScalarFieldValue alpha.water 1 ); } );

速度场

#include "../include/initialConditions" dimensions [0 1 -1 0 0 0 0]; internalField uniform ($velocity 0 0); boundaryField { inlet { type fixedValue; value uniform ($velocity 0 0); } outlet { type inletOutlet; inletValue uniform (0 0 0); value $internalField; } atmosphere { type pressureInletOutletVelocity; value uniform ($velocity 0 0); } bottom { type slip; } front { type symmetryPlane; } back { type symmetryPlane; } }

压力场

dimensions [1 -1 -2 0 0 0 0]; internalField uniform 0; boundaryField { inlet { type fixedFluxPressure; value uniform 0; } outlet { type zeroGradient; } atmosphere { type prghPressure; rho rho; p uniform 0; value uniform 0; // optional initial value } bottom { type fixedFluxPressure; value uniform 0; } front { type symmetryPlane; } back { type symmetryPlane; } }

这个问题卡住好久了，但没有思路调整哪些参数，希望李老师能指点一下

@李东岳 , 李老师您好，我已经在chtMultiRegionFoam中植入了第一张图所示的拉普拉斯及泊松方程，

QQ截图20210619102650.jpg

QQ截图20210619102636.jpg

实现了对电势在流固区域的耦合求解，但电荷的求解似乎不对，然后电场力的求解结果也和参考文章里面差的太多，但我边界设置理论上是符合文章要求的，第二张图和第三张图是我和参考文章计算结果的对比。参考文章及我的算例和编译的求解器链接放在这里：https://pan.baidu.com/s/1U8NBBon8CFVvDoF9Fsi9UA 提取码：mppz
麻烦李老师能抽空看一下，检查一下问题，不胜感激。一个头俩大:136: :136:

QQ截图20210619095212.jpg QQ截图20210619095249.jpg

@conghongchuan 提高一下热度，我可不可以理解成：把气泡替换成旋转机械，就是旋转速度了。

关于网格尺度小了以后interpolation和mapping的问题

这个算例太酷炫了 小液滴都算出来了 还特别圆

@chengan-wang 在 关于codedFixedValue使用 中说：

我定义了ymax，之后如果我使用if ( Cf[faceI].y() > ymax ) 设置相分数，时间步长越来越小。但如果改成if ( Cf[faceI].y() > 0.1 ) 一个具体数值，情况就好很多。我的使用方法是否有问题呢？

理论上不应该有任何问题 :jingya:

@浪迹天大 这样嘛。。。好的，谢谢！

如题，想用Foam-extend里的浸没边界法（Immersed Boundary Method）求解器，解决水与弹性杆的流固耦合数值模拟，有人有这方面经验吗？

@static 你好，我最近也在做三维飞机的相关数值模拟，可否给个联系方式，请教一些问题。谢谢，这是我的qq：3310792254

@李东岳 很抱歉才看到老师的回复。感谢老师，我已经自己解决啦:xinxin:

图挂了

@李东岳 东岳老师，我在dynamicMeshDict里设置了constrints和restraints两个条目，控制圆柱仅在y方向移动，不转动，如下：

constraints { yLine { sixDoFRigidBodyMotionConstraint line; centreOfRotation (0 0 0.5); direction (0 1 0); } noRotation { sixDoFRigidBodyMotionConstraint orientation; } } restraints { verticalSpring { sixDoFRigidBodyMotionRestraint linearSpring; anchor (0 0 0.5); refAttachmentPt (0 0 0.5); stiffness 2.1055; damping 0; restLength 0; } }

不知道您说的是不是这个意思？

@李东岳 感谢李老师百忙之中指点！这么来看correction(fvm::ddt(p))就代表前后时间步压力差值的时间变化率啦

The objective of this link is to provide a resource for CFD developers to:

obtain different gas-liquid benchmark test cases for validation and verification, verify related CFD models are implemented correctly.

This latter capability is made possible through benchmark cases. This site provides simple test cases and grids, along with sample results from experiments which are mainly reported in previous published works. All the test cases are prepared as standard cases for open-source code OpenFOAM-8. It can be run by the following command in the terminal:./Allrun

The site should also help CFD code users to understand and compare the predictions of a variety of models on the fundamental flow problems in the validation database. It also helps developers to disseminate new models to the CFD community.

It is anticipated that this word will be updated regularly as new models and/or verification/validation cases are incorporated and tested. If you have any questions or comments, please contact one of the authors: Dongyue Li (li.dy@dyfluid.com)

1. Diaz et al. 2008

Features: This test case is a laboratory rectangle turbulent bubble column. The gas was injected in the middle of the bottom, which implies the geometry is quite symmetric. Nonetheless, it was also shown that the dynamic periodic liquid circulation can be founded in experiments. Simulations should be able to predict such periodic bubble plume with only the drag model. In addition, the authors also investigated the role of lift force and virtual mass force. The geometry is simple and settings are clear. This test case is suitable for investigate numerical algorithm. It should be noted here that the mean Sauter diameter data was also provided, although not in detail.

Keywords: Unsteady, Rectangle bubble column, Mean Sauter diameter, Bubble plume,

Reference: Díaz et al. "Numerical simulation of the gas–liquid flow in a laboratory scale bubble column: influence of bubble size distribution and non-drag forces." Chemical Engineering Journal 139.2 (2008): 363-379.

bubbleFlow_diaz.jpg

2. Gemello et al. 2018

Features: This test case focuses on the unsteady 3D bubble column operated under high phase fration. Different swarm models were studied and a new swarm model was developed. The diameter of the bubble column ranges from 0.4m to 1m. Different superficial velocities from 0.03 m/s to 0.35 m/s were employed. This test case is suitable for investigate the swarm model correction based on different operating conditions.

Keywords: Unsteady, 3D bubble column, Swarm effect, High phase fraction,

Reference: Gemello et al. "CFD-based scale-up of hydrodynamics and mixing in bubble columns." Chemical Engineering Research and Design 136 (2018): 846-858.

bubbleFlow_Gemello.jpg

3. Lucas et al. 2007

Features: In the work of Lucas et al., bubbly flow in a high aspect ratio column (Column width ~ 0.05 m, Column height ~ 4 m) was investigated. Bubbles and liquid are injected from the bottom. They move upward and at a certain level a fully developed flow pattern is formed. In both experiments and simulations, a quite steady state can be reached at the top of the column. These bubbly flows are operated at relative low phase fraction (~ 3%). The most important feature of the test cases by Lucas et al. is that the momentum exchange interfacial terms play an important role. It was observed in the experiments that the small bubbles tend to move towards to wall. Therefore, a wall peak of the phase fraction should be predicted in simulations. It should be noted here that the lift force, wall lubrication force and turbulent dispersion force should be included.

Keywords: Steady, Bubbly flow, Lift force, Wall forces

Reference: Lucas et al., "Use of models for lift, wall and turbulent dispersion forces acting on bubbles for poly-disperse flows." Chemical Engineering Science 62.15 (2007): 4146-4157.

bubbleFlow_Lucas.jpg

4. Yuan et al. 2014

Features: In the work of Yuan et al., an experimantal quasi-2D bubble column was investigated. In the simulations, 2D computational domain was employed. The bubbles are injected from the bottom of the column with different patterns. Overall 5 patterns were studied. Due to the high superficial velocity, simulations are highly transient. In this work, the QBMM was used to predict bubble diameter. However, the experimental diameter data was not reported. The bubble number density function was also reconstructed by EQMOM. It should be noted here that the experimental data reported in Yuan et al. comes from the PhD thesis of Harteveld, see ref (8) in Yuan et al.

Keywords: Unsteady, Bubble column, 2D simulation

Reference: Yuan et al., "An extended quadrature‐based mass‐velocity moment model for polydisperse bubbly flows." The Canadian Journal of Chemical Engineering 92.12 (2014): 2053-2066.

bubbleFlow_Yuan.jpg

5. Schafer et al. 2019

Features: In the work of Schafer et al., a 3D transient bubble column was studied by experiments and simulations. The geometry used in this work is similar with that used by Diaz et al. The unique feature of this work is that the bubble orientation angle data was provided. It can be used as a benchmark test case for multiphase DNS. Besides that, the bubble diameter NDF was also provided both in experiments and simulations. The so-called SQMOM, as a kind of QBMM, was used predict the bubble NDF at different locations and it was compared with experiments.

Keywords: Unsteady, 3D simulation, NDF reconstruction, SQMOM, Bubble orientation angle

Reference: Schäfer et al., "Experimental investigation of local bubble properties: Comparison to the sectional quadrature method of moments." AIChE Journal 65.10 (2019): e16694.

bubbleFlow_Schafer.jpg

6. Li et al. 2021

Features: In the work of Li et al., three 3D transient bubble column was studied to verify the algorithm. One of test case was reported in Diaz et al. The other one consists of a similar partially aerated rectangle bubble column which was investigated experimentally by Becker et al. in 1994. The left one is an airlift bubble column investigated by Mandalahalli et al. Li et al. developed a new algorithm which is much faster than the traditional Eulerian-Eulerian method and used it to simulate three different bubbly flows as mentioned above. Only drag force needs to be included (the last airlift bubble column also needs the turbulent dispersion force). These test cases are suitable to validate new developed algorithms.

Keywords: Unsteady, 3D simulation, Airlift bubble column, Particlly aerated

Reference: Li et al. "QEEFoam: A Quasi-Eulerian-Eulerian model for polydisperse turbulent gas-liquid flows. Implementation in OpenFOAM, verification and validation." International Journal of Multiphase Flow 136 (2021): 103544.

bubbleFlow_Li.jpg

7. Besbes et al. 2015

Features: In the work of Besbes et al., a needle sparger rectangular bubble column operated at low flow rates was investigated using PIV measurements and Eulerian-Lagrangian simulations. Time-averaged liquid velocity fields from PIV measurements for different flow rate were provided. Snapshots of PIV and Eulerian-Lagrangian simulation of oscillating bubble plume were also supplied. Due to the small flow rate and the usage of a needle sparger, the diameter of bubbles is very homogeneous. The oscillatory movement of bubble plume, as that observed in Diaz et al., was also formed for slightly large flow rate (Q = 0.2 l/min).

Keywords: Needle sparger, Eulerian-Largrangian, PIV

Reference: Besbes et al., "PIV measurements and Eulerian–Lagrangian simulations of the unsteady gas–liquid flow in a needle sparger rectangular bubble column." Chemical Engineering Science 126 (2015): 560-572.

bubbleFlow_Besbes.jpg

8. Darmana et al. 2007

Features: In this work, a rectangle laboratory bubble column was used to study the bubble flow with reactions. A pseudo-2D geometry is chosen to enable visualization of the flow structures by CCD camera and PIV. Lagrangian simulations were also launched. Averaged velocities, bubble plume period, gas holdup and global mean Sauter diameter were also compared with experiments. The species's concentration and Ph value were also provided.

Keywords: Reaction bubble column, Mass transfer, mean Sauter diameter

Reference: Darmana et al. "Detailed modelling of hydrodynamics, mass transfer and chemical reactions in a bubble column using a discrete bubble model: Chemisorption of CO2 into NaOH solution, numerical and experimental study." Chemical Engineering Science 62.9 (2007): 2556-2575.

bubbleFlow_Darmana.jpg

9. Besbes et al. 2020

Features: In this work, the authors employ PIV technique to study the liquid phase flow driven by a chain of air bubbles in a rectangular bubble column. The flow rate is very low that each bubble move upward separately by buoyancy force. Not only water, but also the glycerin solution with high viscosity was studied to understand the liquid flow structure. Bubble terminal velocity and shape were also provided.

Keywords: PIV, Bubble driven flow, High viscosity

Reference: Besbes et al., "Effect of bubble plume on liquid phase flow structures using PIV." Particulate Science and Technology 38.8 (2020): 963-972.

bubbleFlow_Besbes2.jpg

Test Case Diaz et al. 2004 Gemello et al. 2018 Yuan et al. 2014 Lucas et al. 2007 Schafer et al. 2019 Li et al. 2021 Besbes et al. 2015 Darmana et al. 2007 Besbes et al. 2020 Experiments - - - - - - - - - Global holdup - - - - - - - - - Local holdup - - - - - - - - - Liquid velocity - - - - - - - - - Wall effects - - - - - - - - - Turbulent kinetic energy - - - - - - - - - Turbulent dissipation rate - - - - - - - - - Global Sauter diameter - - - - - - - - - Local diameter distribution - - - - - - - - - Local Sauter diameter - - - - - - - - - Reactions - - - - - - - - - Heat transfer - - - - - - - - -

各位大佬好，想请教一下，我想显示一个密度、体积不断变化的物体的质量，请问大家有什么好办法吗？

屏幕截图 2021-06-05 161820.png openfoam自带案例interPhaseChangeFoam求解器下的cavitatingBullet，该图为我跑完0.05s后的水相分布，和0s时没啥变化,请问我哪里错了吗？