# coupled source term in 3 transport equations

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 February 26, 2011, 05:14 coupled source term in 3 transport equations #1 New Member   Muhammad reza hassani Join Date: Apr 2010 Posts: 29 Rep Power: 9 Sponsored Links Dear Foamers I want to revise icoFoam to include three transport equations solving for C1, C2, and C3. the problem is that they are coupled in their source term. I have included "CEqn.H" in my transportFoam (revised icoFoam). I have a constant depending on C3 (third species concentration) which is used in C1, and C2. There are also source term in C2, and C3 equations depending on C1. I faced some questions regarding this: 1st question: Is it correct to use "fvm:Sp(kpa,C1)" in transport equation of C2? or I can simply use "...+ kpa*C1" so it is accounted explicitly? (in the equations kpa and landJ are constants which are calculated and given in transportProperties, respectively) 2nd question: shall I have a loop to converge (solving equations sequentially)? If I do, I have to calculate the difference between each iteration results. Shall I declare a new variable to save each iteration results so I can have comparison in each iteration. 3rd Question:Is it correct to declare and initialize some constants (e.g. omega, kpa in the code below) in the "CEqn.H"? they are to be calculated after C3 equation is solved. //CEqn.H double kpa; // constant calculated after C3 is calculated double omega; //constant calculated after C3 is calculated double C3Crit=2; //a constant solve( fvm::ddt(C3) +fvm::div(phi,C3) -fvm::laplacian(Dm3,C3) -fvm::Sp(landJ,C1) ); omega= C3/C3Crit; if(omega >=1) kpa=omega; else kpa=0; solve ( fvm::ddt(C1) +fvm::div(phi,C1) -fvm::laplacian(Dm1,C1) +fvm::SuSp(kpa,C1) ); //................. solve ( fvm::ddt(C2) +fvm::div(phi,C2) -fvm::laplacian(Dm2,C2) +fvm:Sp(kpa,C1) ) //........... I would appreciate your help. thanks in forward. Best regards

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