Defining non-constant Neumann Boundary Conditon

Question

Andrew Ferguson 2020-1-21

0
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回答： Ravi Kumar 2020-1-22

I am a little unsure if I am using the correct syntax for defining my non-constant neumann boundary condition for a time-dependent PDE.

specifyCoefficients(model,'Face',2,'m',0,'d',1,'c',Da,'a',0,'f',0);
specifyCoefficients(model,'Face',3,'m',0,'d',1,'c',Dg,'a',0,'f',0);
applyBoundaryCondition(model,'neumann','Edge',8,'q',0,'g',@gcoeff2);
function f = gcoeff2(~,state)
rhog = 1250;
rhoa = 1.150;
Da = 2.82*10^-4;
f = (Da.*rhoa./rhog).*(state.ux+state.uy);
end

Esentially I have two areas occupied by different substances, which share a common edge, Edge 8. I want to apply the equal flux boundary condition at edge 8 such that

Is the code for my function correct? Is it necessary for me to add in locations even though the gradient is defined by "state.ux" and "state.uy"? Also, since it is a time dependent PDE do I need to multiply everything by state.time?