Dear friend Who can assist me to write the Binary diffusion coefficient ?? Today ,Five species (includes H2,O2,H2O,N2,CO2)be existed inside the my model. but, i never write any UDF about binary diffusion coefficient . so, you can help me to write a simple program about this problem ... ************* you can refer to this book Book Name is Transport Phenomena Author : Bird ,R., Stewart , W., Lighfoot , E., Year : 1966 ****************** P*Dij(x,y)/[(Pc-i*Pc-j)**(1/3)*(Tc-i*Tc-j)**(5/12)*(1/Mi+1/Mj)**1/2] == 3.64*10**(-8)*[Tcell/(Tc-i*Tc-j)**(1/2)]**2.334

Tc-i critical temperature of cell of species i Tc-j critical temperature of cell of species j Pc-i critical pressure of cell of species i Pc-j critical pressure of cell of species j Mi molecular weight of the species i Mj molecular weight of the species j P total pressure Tcell temperature of cell

************************** Best regard

Hsin-Ping

If your flow is turbulent, and you can be satisfied with fairly good(but not perfect) result, just use Fluent's default value. For turbulent flow, the effcet of the molecular diffusion coefficent is not so significnat because turbulent effect is predominant. You can test it by simple 2D turbulent flow problem by changing the coefficient up to 10~100 times.

If your flow is laminar, just neglect above statement, and be careful for your input.

Sincerely, Jinwook

Dear Dr.Jinwook why the kinetic theory didn't use for laminar flow ???? best regard to you and your family

kevin

[aerospace1365]

hello dear frends,
I want to use transport properties of h2\air in premix combustion. I really need to its transport properties for simulating it by laminar finite rate.
can u help me.