On Thu, Jul 14, 2016 at 10:34 AM, Gopalakrishnan, Krishnakumar
wrote:
> Dear Dan,
>
> Thanks a lot for your reply.
>
> In the 'hacked' source term to handle this special boundary condition, i.e.
>
> fp.ImplicitSourceTerm((mesh.faceNormals * implicitCoeff *
> mesh.facesRight).divergence)),
>
> my i
[0].
Is my understanding correct?
Best Regards
Krishna
-Original Message-
From: fipy-boun...@nist.gov [mailto:fipy-boun...@nist.gov] On Behalf Of Daniel
WheelerTo: 'fipy@nist.gov'
Subject: RE: casting implicit Boundary Conditions in FiPy
I recommend trying both methods and
On Fri, Jul 1, 2016 at 2:44 PM, Gopalakrishnan, Krishnakumar
wrote:
>
> Now, my question is, for the explicit term in the BC, can't I just define in
> a regular Neumann BC style of definition ? , i.e.
> phi.facegrad.constrain([alpha/ (1 - beta*dx/2)], mesh.facesRight]) . i.e.
> will this or
l
Wheeler
Sent: 23 June 2016 15:24
To: Multiple recipients of list
Subject: Re: casting implicit Boundary Conditions in FiPy
On Fri, Jun 17, 2016 at 5:36 PM, Gopalakrishnan, Krishnakumar
wrote:
>
> My problem models the solid diffusion in a spherical particle. Matter
> diffuses fro
> On Jun 23, 2016, at 10:23 AM, Daniel Wheeler
> wrote:
>
> I'm not sure what the thinking is of your colleagues, but the size of
> the elements has little or no impact on conservation. In finite
> volume, the equations are conservative to at least the precision of
> the linear solver (if not m
On Fri, Jun 17, 2016 at 5:36 PM, Gopalakrishnan, Krishnakumar
wrote:
>
> My problem models the solid diffusion in a spherical particle. Matter
> diffuses from the centre of the particle and reacts at the surface. This
> is captured in a normalised 1-D domain with suitable equations and
> co
e 2016 14:50
To: Multiple recipients of list
Subject: Re: casting implicit Boundary Conditions in FiPy
On Thu, Jun 16, 2016 at 12:35 PM, Gopalakrishnan, Krishnakumar
mailto:k.gopalakrishna...@imperial.ac.uk>>
wrote:
> Thanks.
>
> Yes, this Is indeed only first order
:28
To: FIPY
Subject: Re: casting implicit Boundary Conditions in FiPy
Gmsh does do 1D meshes, and I've got experimental code that imports them, but
it's not ready to merge, yet.
In the meantime, this approach I've used for modeling semiconductor device
contacts in 1D is probab
Gmsh does do 1D meshes, and I've got experimental code that imports them, but
it's not ready to merge, yet.
In the meantime, this approach I've used for modeling semiconductor device
contacts in 1D is probably better:
n_thickness = 1e-6 # m
p_thickness = 149e-6 # m
grid_resolution = 5e-8
On Thu, Jun 16, 2016 at 12:35 PM, Gopalakrishnan, Krishnakumar
wrote:
> Thanks.
>
> Yes, this Is indeed only first order accurate. I verified this by
> successively cutting my dx by half, running your code, and comparing against
> the Mathematica generated result. Each time dx is cut by half, t
ing ?
Krishna
-Original Message-
From: fipy-boun...@nist.gov [mailto:fipy-boun...@nist.gov] On Behalf Of Daniel
Wheeler
Sent: 15 June 2016 17:50
To: Multiple recipients of list
Subject: Re: casting implicit Boundary Conditions in FiPy
On Wed, Jun 15, 2016 at 7:27 AM, Gopalakrishnan, Krishnakumar
On Wed, Jun 15, 2016 at 7:27 AM, Gopalakrishnan, Krishnakumar
wrote:
>
> Dan. I was able validate that your code correctly implements the Implicit
> Neumann Boundary Condition (in 1-D).
>
> Here is a link to the plot of the solution after a transient simulation for
> 0.2 seconds. The plot on th
> On Jun 15, 2016, at 7:27 AM, Gopalakrishnan, Krishnakumar
> wrote:
>
> Can we add this as a feature request in the project’s github page, perhaps
> for a future release?
By all means, please file issues on GitHub for any features you'd like or bugs
you find.
_
?
Once again, thanks for your help in providing this solution approach.
Krishna
From: fipy-boun...@nist.gov [mailto:fipy-boun...@nist.gov] On Behalf Of Daniel
Wheeler
Sent: 10 June 2016 18:18
To: Multiple recipients of list
Subject: Re: casting implicit Boundary Conditions in FiPy
Hi Krishina
)
steps = 75
for step in range(steps):
eq.solve(var=phi, dt=timeStep)
viewer.plot()
Krishna
-Original Message-
From: fipy-boun...@nist.gov [mailto:fipy-boun...@nist.gov] On Behalf Of Daniel
Wheeler
Sent: 13 June 2016 03:17
To: Multiple recipients of list
Subject: Re: casting imp
On Sun, Jun 12, 2016 at 8:14 AM, Gopalakrishnan, Krishnakumar
wrote:
>
> 1. The backward Euler method is used in formulating the equation,
> "n.grad(phi) = k * (phi_P + n.grad(phi) * dx / 2) " . But Backward Euler
> is a first order method, isn't it ? I am a bit confused about the second
> o
my head. I have to think about this,
when I implement them perhaps in a week or so.
Thanks once again,
Krishna
From: fipy-boun...@nist.gov on behalf of Daniel Wheeler
Sent: Friday, June 10, 2016 6:17 PM
To: Multiple recipients of list
Subject: Re: casting implic
gt;
>> c.faceGrad.constrain([-(j_at_c_star + partial_j_at_op_point*(c.faceValue
>> - c_star))], mesh.facesTop), then c.faceValue gets immediately
>> evaluated at the operating point, c_star, and we are left with 0
>> multiplying the first-order derivative.
>>
>>
;ithint=photo%2cjpg
>
>
>
> Meanwhile, may I also ask if other Fipy users or developers had to deal
> with non-linear Implicit Neumann boundary conditions in their problems?
>
>
>
>
>
> Krishna
>
>
>
> *From:* fipy-boun...@nist.gov [mailto:fipy-boun...@nist.
lue substitution, we are simply left with
>
>
>
>
>
> i.e. evaluation of the j at a given DC operating point, introducing first
> order errors in the local time-step.
>
>
>
> Am I on the wrong track here ?
>
>
>
>
>
> Krishna
>
>
>
> *F
: Re: casting implicit Boundary Conditions in FiPy
Hi, Krishna.
Perhaps I'm misunderstanding something, but I'm still not convinced the second
version you suggested -- c.faceGrad.constrain([-(j_at_c_star +
partial_j_at_op_point*(c.faceValue - c_star))], mesh.facesTop) -- isn't wo
ated
> at the operating point, c_star, and we are left with 0 multiplying the
> first-order derivative.
>
>
>
> ie. the Boundary conditions becomes,
>
>
>
> Leading to huge loss of accuracy.
>
>
>
> Is there any hope at all in this situation ? J . Cheers and tha
: fipy@nist.gov
Subject: Re: casting implicit Boundary Conditions in FiPy
Hi, Krishna.
Could you give a bit more detail and/or an example about how you know it's
doing the wrong thing throughout the solution process? In the example you sent,
the correct solution is the same (c(x, t) = 0) wh
icit.
>>
>>
>>
>> In FiPy, I have previously set up an implicit source term,by using
>> the following code snippet, ImplicitSourceTerm(coeff=k) . Perhaps there
>> might be an equivalent method in FiPy to set up the implicit BC, I think ?
>>
>>
>&
code snippet, ImplicitSourceTerm(coeff=k) . Perhaps there
> might be an equivalent method in FiPy to set up the implicit BC, I think ?
>
>
>
>
>
> Krishna
>
>
>
>
>
>
>
>
>
> *From:* fipy-boun...@nist.gov [mailto:fipy-boun...@nist.gov] *On Behal
ymond
Smith
Sent: 09 June 2016 14:23
To: fipy@nist.gov
Subject: Re: casting implicit Boundary Conditions in FiPy
Oh, right, the boundary condition is applied on a face, so you need the
facevalue of phi:
phi.faceGrad.constrain([phi.harmonicFaceValue])
Ray
On Thu, Jun 9, 2016 at 7:28 AM, Gopalakri
ng the implicit BC within the time-stepper loop, but
> that does not still help.
>
>
>
>
>
> Best Regards
>
>
>
> Krishna
>
>
>
>
>
>
>
> *From:* fipy-boun...@nist.gov [mailto:fipy-boun...@nist.gov] *On Behalf
> Of *Gopalakrishnan, Krishna
st Regards
Krishna
From: fipy-boun...@nist.gov [mailto:fipy-boun...@nist.gov] On Behalf Of
Gopalakrishnan, Krishnakumar
Sent: 08 June 2016 23:42
To: fipy@nist.gov
Subject: RE: casting implicit Boundary Conditions in FiPy
Hi Raymond,
Sorry, it was a typo.
Yes, It is indeed d (phi)/dx
Behalf Of Raymond
Smith
Sent: 08 June 2016 23:36
To: fipy@nist.gov
Subject: Re: casting implicit Boundary Conditions in FiPy
Hi, Krishna.
Just to make sure, do you mean that the boundary condition is a derivative with
respect to the spatial variable or with respect to time as-written? If you mean
Hi, Krishna.
Just to make sure, do you mean that the boundary condition is a derivative
with respect to the spatial variable or with respect to time as-written? If
you mean spatial, such that d\phi/dx = k*phi, have you tried
phi.faceGrad.constrain(k*phi) and that didn't work?
If you mean that its
I am trying to solve the standard fickean diffusion equation on a 1D uniform
mesh in (0,1)
$$\frac{\partial \phi}{\partial t} = \nabla.(D \nabla\phi)$$
with a suitable initial value for $\phi(x,t)$.
The problem is that, one of my boundary conditions is implicit, i.e. is a
function of the field
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