DPMFoam设置求解问题



  • 最近在使用DPMFoam进行EL流固耦合模拟,对于kinematicCloudProperties和fvsolution文件有些不太明白,想请教各位老师。

    1. kinematicCloudProperties solution中设置coupled true是否就直接将four way coupling改为one way了,还需要进行其他修改吗?
    2. kinematicCloudProperties injectionmodelsInitial parcel/particle velocity U0如何设置为与流体相具有相同的速度分布?
      air inlet velocity是用codedFixedValue给出:
    code            #{
                const fvPatch& boundaryPatch = this->patch();
    
                vectorField v = boundaryPatch.Cf();
    
                //scalar xmax = max(patch().Cf()&vector(1,0,0));
                //scalar xmin = min(patch().Cf()&vector(1,0,0));
                //scalar zmax = max(patch().Cf()&vector(0,0,1));
                //scalar zmin = min(patch().Cf()&vector(0,0,1));
                scalar rmax = 5.45e-4;
                scalar vmax = 1.0465;//Q = 60 vmax = 1.0465; Q = 120 vmax = 2.0931
                
                //Info<<"xmax="<<xmax<<nl;
    
                forAll(boundaryPatch, faceI)
                {
                //spatial coordinates, type: scalar
                scalar x = boundaryPatch.Cf()[faceI].x();
                //scalar y = Cf[faceI].y();
                scalar z = boundaryPatch.Cf()[faceI].z();
                            
                v[faceI] = vector(0, vmax*(sqr(rmax)-sqr(x)-sqr(z))*1e06, 0); 
                }
                
                operator==(v);
            #};
    
    1. kinematicCloudProperties injectionmodelsflowRateProfile 是什么呢?如何进行设置?
    2. 能否在kinematicCloudProperties injectionmodels中设置点云出现概率与速度分布呈正比呢?如果不行能否在每次求解完成后更新injection point cloud?
    3. fvSolution文件中求解器的使用是否对solution cost和converge有影响,之前做纯气流用GAMG比较多,其他的求解器基本没有接触过,目前求解器是这样设置的:
    solvers
    {
        "(p|kinematicCloud:theta)"
        {
            solver          PCG;
            preconditioner	DIC;
            tolerance       1e-06;
            relTol          0.01;
            smoother        GaussSeidel;
        }
    
        "(p|kinematicCloud:theta)Final"
        {
        	solver          PCG;
            preconditioner	DIC;
            tolerance       1e-06;
            //relTol          0.01;
            smoother        GaussSeidel;
        }
        "(U.air|k.air|epsilon.air)"
        {
            solver          PBiCGStab;
            preconditioner	DILU;
            smoother        symGaussSeidel;
            tolerance       1e-05;
            relTol          0.1;
        }
    
        "(U.air|k.air|epsilon.air)Final"
        {
            solver          PBiCGStab;
            preconditioner	DILU;
            tolerance       1e-05;
            relTol          0;
        }
    }
    


  • 自己来回复一下吧!

    • 对于颗粒负载不高的气固两相流,关闭coupling设置为oneway能获得比较符合实际的结果。

    • kinematicCloudProperties injectionmodelsflowRateProfile设置为1表示颗粒与流体在入口速度相同。

    • PCG+PBiCGStab相比GAMG+smoothslover花费时间更多,鲁棒性上还没去细看。



  • 您好,请问coupled true 是指四向耦合,coupled false 是指单向耦合吗,one way仅仅表示液相对颗粒相具有作用力吗,谢谢



  • 四项耦合需要考虑颗粒之间的碰撞 oneway是单项耦合



  • @veen 更正一下kinematicCloudProperties injectionmodels中flowRateProfile 表示的是实际质量流量和设置流量之间的关系



  • @upc_ngh 目前我看到的资料是这样说的,设置为false就是one way,具体couple的源代码我没去细看。

    From http://cfdyna.com/Home/of_multiPhase.html

    One-way coupling or uncoupled approach: fluid → particles - this is appropriate only with very dilute concentration (< 0.01% volume fraction) of particles and has no significant effect on turbulence. The flow field is calculated assuming no presence of particle - fixed continuous phase flow field (that is before the particles is injected into the flow) and tracked as they injected into the flow. The particles does not interact with any other particles during its track throughout the flow domain.

    Two-way coupling: fluid ↔ particles - this coupling becomes important when the volume fraction of particles is in the range 0.01% - 10% and affects both dissipation and production of TKE. The flow of fluid is necessarily solved along with the movement for Lagrangian particles. This is enabled in ANSYS FLUENT by switching on "Interaction with Continuous Phase" option in the Discrete Phase Model dialog box. To control the frequency at which the particles are tracked and the DPM sources are updated, "Number of Continuous Phase Iterations per DPM Iteration" option exists. Option "Update DPM Sources Every Flow Iteration" is available for unsteady simulations.

    Four-way coupling: fluid ↔ particles + particle collisions: the particle - particle interaction becomes important if volume fraction of particles is > 10%. Note that the mass fraction can be still higher due to large difference in the densities of the solid and gas / liquid.



  • @东岳 李老师,有没有可能在DPMFoam里边设置每步生成随机的点云啊?我看patch injection是根据面网格密度生成的点云,而且网格越密的地方粒子越多。目前我是用多个点云injection去替代的,我在想有没有方法可以实现,自定义点云的分布密度呢?


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