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  3. reactingtwophaseeulerfoam?

reactingtwophaseeulerfoam?

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  • K Offline
    K Offline
    kimy
    replied to 李东岳 on last edited by
    #10

    @东岳 Frankly, I use the minus sign and I got the results however they doesn't agree well with the results from PHOENICS. The velocity profile seems shift in some degree. So I would like to try "plus" this term. I am not sure the place I added is right or not. When I change one to be plus and the other to be minus, it runs well and the results seems better.

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  • 李东岳李 Online
    李东岳李 Online
    李东岳 管理员
    wrote on last edited by
    #11

    You cannot implement equations as you want. What you implement should obey physics. Otherwise even you get "reasonable" results, its just coincidence.

    9月CFD算法编程课: http://dyfluid.com/class.html

    需要帮助debug算例的看这个 https://cfd-china.com/topic/8018

    K 2 Replies Last reply
  • K Offline
    K Offline
    kimy
    replied to 李东岳 on last edited by
    #12

    @东岳 I see. That is the reason why I post here. I wanna be sure that term should be implemented in which place. This is what I expect. Do you have any idea?

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  • K Offline
    K Offline
    kimy
    replied to 李东岳 on last edited by
    #13

    @东岳 I am using IPSA model (lauder and spalding). In all of equation used, the alpha term has been introduced inside.
    http://www.cham.co.uk/phoenics/d_polis/d_lecs/ipsa/ipsa.htm#11

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  • K Offline
    K Offline
    kimy
    replied to 李东岳 on last edited by 李东岳
    #14

    @东岳 Sorry. I am still confused that how the equation(24) mentioned in your page could be solved in OpenFoam. In the source code:

            solve
            (
                pEqnComp1() + pEqnComp2() + pEqnIncomp,
                mesh.solver(p_rgh.select(pimple.finalInnerIter()))
            );
    

    why pEqnComp1() + pEqnComp2() + pEqnIncomp ranther than - pEqnComp1() - pEqnComp2() + pEqnIncomp. Because in your equation(24), pEqnComp1() + pEqnComp2() in the right side while pEqnIncomp in the left side.

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  • 李东岳李 Online
    李东岳李 Online
    李东岳 管理员
    wrote on last edited by 李东岳
    #15

    Thanks for your feedback. The R.H.S. of the following equation should be a - sign. It was corrected.
    \begin{equation}\label{comp_nablaU}
    \underset{\mathrm{pEqnIncomp}}{\underbrace{\nabla\cdot\left(\alpha_\rd\bfU_\rd+\alpha_\rc\bfU_\rc\right)}}=\underset{\mathrm{\color{red}{-}pEqnComp1\color{red}{-}pEqnComp2}}{\underbrace{-\frac{\alpha_\rd}{\rho_\rd}\frac{\rD\rho_\rd}{\rD t}-\frac{\alpha_\rc}{\rho_\rc}\frac{\rD\rho_\rc}{\rD t} }}.
    \end{equation}

    What is the first term? Its a second order tensor which is not consistent with the second term (scalar).

    替代文字

    9月CFD算法编程课: http://dyfluid.com/class.html

    需要帮助debug算例的看这个 https://cfd-china.com/topic/8018

    K 2 Replies Last reply
  • K Offline
    K Offline
    kimy
    replied to 李东岳 on last edited by
    #16

    @东岳 So if I wanna add the term related to the gradient alpha in the continuity equation, in which place should I put the term?

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  • K Offline
    K Offline
    kimy
    replied to 李东岳 on last edited by
    #17

    @东岳 Thanks, Dongyue. I am still confused that why I add the same term in the pEqnComp1 and pEqnComp2, or pEqnIncomp leads to the different results?

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  • 李东岳李 Online
    李东岳李 Online
    李东岳 管理员
    wrote on last edited by
    #18

    So if I wanna add the term related to the gradient alpha in the continuity equation, in which place should I put the term?

    You should implement it in the alpha equation.

    9月CFD算法编程课: http://dyfluid.com/class.html

    需要帮助debug算例的看这个 https://cfd-china.com/topic/8018

    K 1 Reply Last reply
  • K Offline
    K Offline
    kimy
    replied to 李东岳 on last edited by
    #19

    @东岳 Sorry, to my knowledge alpha equation dosn't exsist in the twophaseeulerfoam? How can I realize it?

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  • 李东岳李 Online
    李东岳李 Online
    李东岳 管理员
    wrote on last edited by
    #20

    alpha field was solved by MULES algorithm. You can add something after MULES procedure as follows:

    solve(fvm::ddt(alpha) - fvm::laplacian(D, alpha) = fvc::ddt(alpha);
    

    9月CFD算法编程课: http://dyfluid.com/class.html

    需要帮助debug算例的看这个 https://cfd-china.com/topic/8018

    K 1 Reply Last reply
  • K Offline
    K Offline
    kimy
    replied to 李东岳 on last edited by
    #21

    @东岳Thanks. however MULES is not implemented in twophaseeulerfoam. As mentioned before, the term must be added into the continuity equation rather than alpha equa, which is the Spalding's IPSA solver in PHOENICS.

    K 1 Reply Last reply
  • K Offline
    K Offline
    kimy
    replied to kimy on last edited by
    #22

    @kimy Sorry, I mean where is the MULES in the twophaseeulerfoam, which I did not find but I found MULES in the terminal during calculation.

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  • 李东岳李 Online
    李东岳李 Online
    李东岳 管理员
    wrote on last edited by
    #23

    alpha was solved in twoPhaseSystem.C

    9月CFD算法编程课: http://dyfluid.com/class.html

    需要帮助debug算例的看这个 https://cfd-china.com/topic/8018

    1 Reply Last reply

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