In the website above, equation(24) is the sum of two continuity equations. Thus, I think the source term should be added here? Please give me some suggestions.

```
pEqnComp1 =
(
contErr1
- fvc::Sp(fvc::ddt(alpha1) + fvc::div(alphaPhi1), rho1)
)/rho1
+ (alpha1*psi1/rho1)*correction(fvm::ddt(p_rgh))
+ fvc::laplacian(phase2.turbulence().nut()/mysigma,alpha1);
```

The last line is added by myself, also for pEqnComp1. I don't know why it can be run with minus that bold term while I changed the sign to be plus the simulation crashed.

]]>In the website above, equation(24) is the sum of two continuity equations. Thus, I think the source term should be added here? Please give me some suggestions.

```
pEqnComp1 =
(
contErr1
- fvc::Sp(fvc::ddt(alpha1) + fvc::div(alphaPhi1), rho1)
)/rho1
+ (alpha1*psi1/rho1)*correction(fvm::ddt(p_rgh))
+ fvc::laplacian(phase2.turbulence().nut()/mysigma,alpha1);
```

The last line is added by myself, also for pEqnComp1. I don't know why it can be run with minus that bold term while I changed the sign to be plus the simulation crashed.

]]>t is a laplacian term. A positive laplacian term u

Thanks a lot, dongyue. I check the term I implemented are both the positive and negative values. Why minus has no problem and plus occurs the problem. Sorry, what do you mean follow my step to introduce a dispersion force as source term? and Another operator is?How to split ? One thing needs to be clear, here I did not use Sp or SuSp, but do you think it will lead different results?

]]>This is the mass conservation equation I am using. The sign of laplacian term here is minus. However, as your page http://dyfluid.com/reactingTwoPhaseEulerFoam.html in equation(24), it should be plus I think if I understand well. I am confused that the sign of source term will induce large different result or no? ]]>

why I use the sign "plus", it crashed while 'minus' run well? And if I changed the phase2.turbulence.nut() to be nu() a constant, "plus" has no problem?

Do you obtain physically reasonable results? or just not blowing up.

]]>http://www.cham.co.uk/phoenics/d_polis/d_lecs/ipsa/ipsa.htm#11 ]]>

```
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.

`-`

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).

]]>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.

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

]]>`twoPhaseSystem.C`

]]>