Hi All,
I tried to implement this approach in my problem, and encountered some
problems. To keep this post more general, I posted the pseudo code, and
point out the problem. I could also send the actual code in private if
someone is willing to take a look at it.
Basically, I have two 2D gmsh created irregular mesh that connected to each
other. I am trying to "copy" the value from the boundary of mesh_1, into
the mesh_2. Please note that mesh_1 and mesh_2 both share this boundary.
After playing around the gmsh, I found that I could draw two fields
together. However, when I actually created the surface, I only created the
surface corresponding to mesh_1 and mesh_2
mesh_1 = Gmsh2D(''
........
Line Loop(9) = {6,7, 8,5};
Line Loop(10) = {-6,-5,9};
Plane Surface (11) = {9};
Physical Surface("flowinglayer") = {11};
Physical Line("Bottom_Left") = {5};
Physical Line("Bottom_Right") = {6};
''' % locals())
mesh_2 = Gmsh2D('''
.........
Line Loop(9) = {6,7, 8,5};
Line Loop(10) = {-6,-5,9};
Plane Surface (12) = {10};
Physical Surface("bulkflow") = {12};
Physical Line("Bottom_Left") = {5};
Physical Line("Bottom_Right") = {6};
''' % locals())
As you could see, mesh_1 only corresponding to line loop 9, mesh_2 only
corresponding to line loop 10. The reason I do this is it allows the mesh
between the interface of the mesh_1 and mesh_2 to mesh properly. Then I
created variable to transfer data, as suggested by Ian.
inlet_BC_value = Variable(value = 0.5, array = numerix.zeros((1,102)))
phi_2.constrain(inlet_BC_value, where = mesh_2.exteriorFaces &
mesh_2.physicalFaces["Bottom_Right"])
Finally, solve the equation and update this "inlet_BC_value"
for step in range(steps):
res_1 = 1000
res_2 = 1000
inlet_BC_value_new = phi_1.faceValue[(mesh_1.exteriorFaces &
mesh_1.physicalFaces["Bottom_Right"]).value]
inlet_BC_value.value = np.float64(inlet_BC_value_new)
while np.maximum(res_1,res_2) > 1e-4:
res_1 = eq_1.sweep(var=phi_1,dt=timeStepDuration)
res_2 = eq_2.sweep(var=phi_2,dt=timeStepDuration) # doctest: +GMSH
phi_1.updateOld()
phi_2.updateOld()
viewer_1.plot()
viewer_2.plot()
print step
On Wed, Oct 12, 2016 at 11:14 PM, Zhekai Deng <
zhekaideng2...@u.northwestern.edu> wrote:
> I see. Thanks for clarifying it ! I will implement this over the weekend
> and to see how it works out. Thank you.
>
> Best,
>
> Zhekai
>
> On Wed, Oct 12, 2016 at 8:15 AM, Campbell, Ian <
> i.campbel...@imperial.ac.uk> wrote:
>
>> Dear Zhekai,
>>
>>
>>
>> My October 11th post to this list affects my recommendation to you from
>> October 4th. You’ll probably be fine if you aren’t running your simulation
>> for long, but if you are running it for long periods, it will likely become
>> cripplingly slow. I've implemented the corrected version below for you,
>> which should not have a memory leak because of the method of updating the
>> boundary condition.
>>
>>
>>
>> I hope that helps.
>>
>>
>>
>> Best regards,
>>
>>
>>
>> - Ian
>>
>>
>>
>> phi_1_initial, phi_2_initial = 0.0, 0.0
>> D1, D2 = 1.5, 1.75
>>
>> dx_1 = [0.03806023, 0.10838638, 0.16221167, 0.19134172, 0.19134172,
>> 0.16221167, 0.10838638, 0.03806023]
>> dx_2 = [0.03806023, 0.10838638, 0.16221167, 0.19134172, 0.19134172,
>> 0.16221167, 0.10838638, 0.03806023]
>>
>> mesh_1 = Grid1D(dx=dx_1, Lx=1.0)
>> mesh_2 = Grid1D(dx=dx_2, Lx=1.0)
>>
>> phi_1 = CellVariable(mesh_1, value=phi_1_initial)
>> phi_2 = CellVariable(mesh_2, value=phi_2_initial)
>>
>> eq_1 = TransientTerm() == ExplicitDiffusionTerm(coeff=D1)
>> eq_2 = TransientTerm() == ExplicitDiffusionTerm(coeff=D2)
>>
>> phi_1.faceGrad.constrain(0.5, where=mesh_1.facesLeft)
>> phi_1.constrain(1.0, where=mesh_1.facesRight)
>> inlet_BC_value = Variable()
>> phi_2.faceGrad.constrain(inlet_BC_value, where=mesh_2.facesLeft)
>> phi_2.faceGrad.constrain(-0.5, where=mesh_2.facesRight)
>>
>> timeStepDuration = 0.9 * min(dx_1)**2 / (2 * max(D1, D2))
>> steps = 100
>> viewer = Viewer(vars=(phi_1, phi_2))
>>
>> for step in range(steps):
>> eq_1.solve(var=phi_1, dt = timeStepDuration)
>> inlet_BC_value_new = phi_1.faceValue[mesh_2.faceCenters == 1.0]
>> # Acquire the data
>> inlet_BC_value.setValue(float(inlet_BC_value_new))
>> # Apply that data on the 2nd mesh
>> eq_2.solve(var=phi_2, dt = timeStepDuration)
>> viewer.plot()
>>
>>
>>
>>
>>
>> *From:* fipy-boun...@nist.gov [mailto:fipy-boun...@nist.gov] *On Behalf
>> Of *Zhekai Deng
>> *Sent:* 05 October 2016 05:20
>> *To:* fipy@nist.gov
>> *Subject:* Re: how to set up data transfer between two adjacent
>> nonuniform meshs
>>
>>
>>
>> Hi Ian,
>>
>>
>>
>> Thank you very much for the example and pointing out the additional
>> reference. Those are very useful informations. This approach seems
>> intuitive and easy to incorporate into the code. I will try to incorporate
>> it into my own code. Thanks again.
>>
>>
>>
>> Best,
>>
>>
>>
>> Zhekai
>>
>>
>>
>> On Tue, Oct 4, 2016 at 5:23 AM, Campbell, Ian <
>> i.campbel...@imperial.ac.uk> wrote:
>>
>> Hi Zhekai,
>>
>>
>>
>> There is.
>>
>>
>>
>> Try the following, where as you suggest, the interpolated value at the
>> right-most face of mesh_1 is used. That (outward flowing) flux value is
>> then copied to the inlet boundary condition (Neumann/flux) for mesh_2. A
>> diffusion equation with a different coefficient for your solution variable
>> phi is defined on the 2nd mesh – this should work if you change the
>> equation further. Both meshes are non-uniform and of unit length.
>>
>>
>>
>> I don’t know from your question what type or magnitude boundary
>> conditions you’re interested in on the other faces, but nonetheless, you
>> can see in the figures produced from the code below that the outlet flux on
>> the right-most face of mesh_1 is equal to the inlet flux on the left-most
>> face of mesh_2. There’s likely a cleaner way to do this, by updating the
>> value of the boundary condition for mesh_2 rather than re-defining it, but
>> this is a start.
>>
>>
>>
>> An additional reference for you, here is Dr. Guyer’s suitably-named Gist:
>> https://gist.github.com/guyer/bb199559c00f6047d466daa18554d83d
>>
>>
>>
>> Let us know if that works for you.
>>
>>
>>
>> Best,
>>
>>
>>
>> - Ian
>>
>>
>>
>> phi_1_initial, phi_2_initial = 0.0, 0.0
>>
>> D1, D2 = 1.5, 1.75
>>
>> inlet_BC_value_init = 2.0
>>
>>
>>
>> dx_1 = [0.03806023, 0.10838638, 0.16221167, 0.19134172, 0.19134172,
>> 0.16221167, 0.10838638, 0.03806023]
>>
>> dx_2 = [0.03806023, 0.10838638, 0.16221167, 0.19134172, 0.19134172,
>> 0.16221167, 0.10838638, 0.03806023]
>>
>>
>>
>> mesh_1 = Grid1D(dx=dx_1, Lx=1.0)
>>
>> mesh_2 = Grid1D(dx=dx_2, Lx=1.0)
>>
>>
>>
>> phi_1 = CellVariable(mesh_1, value=phi_1_initial)
>>
>> phi_2 = CellVariable(mesh_2, value=phi_2_initial)
>>
>>
>>
>> eq_1 = TransientTerm() == ExplicitDiffusionTerm(coeff=D1)
>>
>> eq_2 = TransientTerm() == ExplicitDiffusionTerm(coeff=D2)
>>
>>
>>
>> # Boundary Conditions
>>
>> phi_1.faceGrad.constrain(0.5, where=mesh_1.facesLeft)
>>
>> phi_1.constrain(1.0, where=mesh_1.facesRight)
>>
>> phi_2.faceGrad.constrain(inlet_BC_value_init, where=mesh_2.facesLeft)
>>
>> phi_2.faceGrad.constrain(-0.5, where=mesh_2.facesRight)
>>
>>
>>
>> timeStepDuration = 0.9 * min(dx_1)**2 / (2 * max(D1, D2))
>>
>> steps = 100
>>
>> viewer = Viewer(vars=(phi_1, phi_2))
>>
>>
>>
>> for step in range(steps):
>>
>> eq_1.solve(var=phi_1, dt = timeStepDuration)
>>
>> inlet_BC_value = phi_1.faceValue[mesh_2.faceCenters == 1.0]
>> # Acquire the data
>>
>> phi_2.faceGrad.constrain(inlet_BC_value, where=mesh_2.facesLeft)
>> # Apply that data on the 2nd mesh
>>
>> eq_2.solve(var=phi_2, dt = timeStepDuration)
>>
>> viewer.plot()
>>
>>
>>
>> *From:* fipy-boun...@nist.gov [mailto:fipy-boun...@nist.gov] *On Behalf
>> Of *Zhekai Deng
>> *Sent:* 04 October 2016 03:29
>> *To:* fipy@nist.gov
>> *Subject:* how to set up data transfer between two adjacent nonuniform
>> meshs
>>
>>
>>
>> Hello All,
>>
>>
>>
>> I wonder is there any way to allow the data share on the two nonuniform
>> mesh's interface ? To explain this, let's say I have two meshes, mesh_1 and
>> mesh_2. Different equations govern the mesh_1 and mesh_2, and solution
>> variable on both meshes is phi. I would like the outlet (on the right
>> face) on mesh_1 served as inlet(on the left face) on mesh_2.
>>
>>
>>
>> I tired to concatenate two mesh. If they are uniform, this works fine.
>> However, if two does not share the exact the same face (for example, one is
>> uniform, and another is nonuniform), there seems to be problem. .
>>
>>
>>
>> Thus, I wonder is there any way to "interpolate" the phi.facevalue on
>> mesh_1 outlet face, and apply this interpolation value into the inlet of
>> mesh_2?
>>
>>
>>
>>
>>
>> Best,
>>
>>
>>
>> Zhekai
>>
>>
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>>
>>
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>>
>
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