PDE Toolbox - Convection in Diffusion Equation

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Andrew Ferguson
Andrew Ferguson 2020-1-21
评论： Gobinda Debnath 2023-7-23
I'm trying to add a convection term to solve a diffusion PDE using the PDE Toolbox. I'm defining the PDE as:
specifyCoefficients(model,'Face',2,'m',0,'d',1,'c',Da,'a',0,'f',@fcoeff);
and have the following at the end of my code:
function f = fcoeff(location,state)
y = location.y./h;
x = location.x./L;
v = va;
f = -(v.*state.ux.*state.time + v.*state.uy.*state.time);
end
However, whenever I try to run the code I get the following error:
Error using pde.CoefficientAssignment/checkCoefFcnHdlArgCounts (line 499)
Function specifying a coefficient must accept two
input arguments and return one output argument.
Error in pde.CoefficientAssignment/checkFcnHdlArgCounts (line 272)
self.checkCoefFcnHdlArgCounts(self.f, systemsize, ndims);
Error in pde.CoefficientAssignment (line 104)
obj.checkFcnHdlArgCounts(systemsize, numdims);
Error in pde.PDEModel/specifyCoefficients (line 143)
coef = pde.CoefficientAssignment(self.EquationCoefficients,argsToPass{:});
Error in Dry_Air (line 49)
specifyCoefficients(model,'Face',2,'m',0,'d',1,'c',Da,'a',0,'f',@fcoeff);
I don't understand the error because as I see it I am ipnuting two arguments and am returning one output. Whenever I take away the function for 'f' on the RHS of the PDE my code works perfectly. Any help would be much appreciated!

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采纳的回答

Ravi Kumar
Ravi Kumar 2020-1-21
It looks like your function errored without returning one onput. Most likely the error could have been due to 'va' being out of scope for the function fcoeff.
Regards,
Ravi
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Gobinda Debnath
Gobinda Debnath 2023-7-23
Hello Andrew ferguson and ravi sir, i am new to matlab, can i get a sample code for convection-diffusion term equation, in matlab how to handle convection term, please help me on this, thank you

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