## Error in applyBoundaryCondition: symmetry boundary condition

Hello everyone! I am modelling the cross section of the pipe of a heat exchanger. The following below is an isothermal case.

My issue was that I could not set a symmetry boundary condition, i.e. at the center of the cross section (r=0) there is no heat transfer. Therefore, I created a very small rectangle R1 to apply the condition to. I tried to select it as a "Face" in the applyBoundaryCondition command, but I got an error. I tried using all the rectangle edges (1:4) and I am now getting the following error:

Incorrect number or types of inputs or outputs for function applyBoundaryCondition.

I even tried to change the line to:

applyBoundaryCondition(model,"neumann","Edge",1:4,"q",[0;0;0;0],"g",[0;0;0;0])

but still nothing. Could anybody suggest what the problem is? Thank you!

See my full code below!

model = createpde()

k = 0.6; %W/mK=W/mC

R = 0.05; %m

r = R; %m

interior = [0,0];

pdecirc(0,0,R); % only radial transfer considered due to large z assumption % Tell Mae we use the PDE Toolkit

pderect([-0.00001 0.00001 -0.00001 0.00001],’R1′)

g = decsg(gd,sf,ns);

geometryFromEdges(model,g)

model = femodel(AnalysisType="thermalSteady", …

Geometry=g);

pdegplot(model,EdgeLabels="on")

title(‘Pipe Cross Section’)

xlim([-0.1,0.1])

ylim([-0.1,0.1])

model.MaterialProperties=materialProperties(ThermalConductivity=k);

model.EdgeBC(5) = edgeBC(Temperature=T0); % isothermal

model.EdgeBC(6) = edgeBC(Temperature=T0); % isothermal

model.EdgeBC(7) = edgeBC(Temperature=T0); % isothermal

model.EdgeBC(8) = edgeBC(Temperature=T0); % isothermal

applyBoundaryCondition(model,"neumann","Edge",1:4,"q",0,"g",0) %See documentation with the generic form for Neumann BC’sHello everyone! I am modelling the cross section of the pipe of a heat exchanger. The following below is an isothermal case.

My issue was that I could not set a symmetry boundary condition, i.e. at the center of the cross section (r=0) there is no heat transfer. Therefore, I created a very small rectangle R1 to apply the condition to. I tried to select it as a "Face" in the applyBoundaryCondition command, but I got an error. I tried using all the rectangle edges (1:4) and I am now getting the following error:

Incorrect number or types of inputs or outputs for function applyBoundaryCondition.

I even tried to change the line to:

applyBoundaryCondition(model,"neumann","Edge",1:4,"q",[0;0;0;0],"g",[0;0;0;0])

but still nothing. Could anybody suggest what the problem is? Thank you!

See my full code below!

model = createpde()

k = 0.6; %W/mK=W/mC

R = 0.05; %m

r = R; %m

interior = [0,0];

pdecirc(0,0,R); % only radial transfer considered due to large z assumption % Tell Mae we use the PDE Toolkit

pderect([-0.00001 0.00001 -0.00001 0.00001],’R1′)

g = decsg(gd,sf,ns);

geometryFromEdges(model,g)

model = femodel(AnalysisType="thermalSteady", …

Geometry=g);

pdegplot(model,EdgeLabels="on")

title(‘Pipe Cross Section’)

xlim([-0.1,0.1])

ylim([-0.1,0.1])

model.MaterialProperties=materialProperties(ThermalConductivity=k);

model.EdgeBC(5) = edgeBC(Temperature=T0); % isothermal

model.EdgeBC(6) = edgeBC(Temperature=T0); % isothermal

model.EdgeBC(7) = edgeBC(Temperature=T0); % isothermal

model.EdgeBC(8) = edgeBC(Temperature=T0); % isothermal

applyBoundaryCondition(model,"neumann","Edge",1:4,"q",0,"g",0) %See documentation with the generic form for Neumann BC’s Hello everyone! I am modelling the cross section of the pipe of a heat exchanger. The following below is an isothermal case.

My issue was that I could not set a symmetry boundary condition, i.e. at the center of the cross section (r=0) there is no heat transfer. Therefore, I created a very small rectangle R1 to apply the condition to. I tried to select it as a "Face" in the applyBoundaryCondition command, but I got an error. I tried using all the rectangle edges (1:4) and I am now getting the following error:

Incorrect number or types of inputs or outputs for function applyBoundaryCondition.

I even tried to change the line to:

applyBoundaryCondition(model,"neumann","Edge",1:4,"q",[0;0;0;0],"g",[0;0;0;0])

but still nothing. Could anybody suggest what the problem is? Thank you!

See my full code below!

model = createpde()

k = 0.6; %W/mK=W/mC

R = 0.05; %m

r = R; %m

interior = [0,0];

pdecirc(0,0,R); % only radial transfer considered due to large z assumption % Tell Mae we use the PDE Toolkit

pderect([-0.00001 0.00001 -0.00001 0.00001],’R1′)

g = decsg(gd,sf,ns);

geometryFromEdges(model,g)

model = femodel(AnalysisType="thermalSteady", …

Geometry=g);

pdegplot(model,EdgeLabels="on")

title(‘Pipe Cross Section’)

xlim([-0.1,0.1])

ylim([-0.1,0.1])

model.MaterialProperties=materialProperties(ThermalConductivity=k);

model.EdgeBC(5) = edgeBC(Temperature=T0); % isothermal

model.EdgeBC(6) = edgeBC(Temperature=T0); % isothermal

model.EdgeBC(7) = edgeBC(Temperature=T0); % isothermal

model.EdgeBC(8) = edgeBC(Temperature=T0); % isothermal

applyBoundaryCondition(model,"neumann","Edge",1:4,"q",0,"g",0) %See documentation with the generic form for Neumann BC’s boundary condition MATLAB Answers — New Questions