Attempt at radiation as a pseudo-boundary condition #855
Conversation
This file contains bidirectional Unicode text that may be interpreted or compiled differently than what appears below. To review, open the file in an editor that reveals hidden Unicode characters.
Learn more about bidirectional Unicode characters
majosm
force-pushed
the
tulio/prod-radiation
branch
from
d0269c7
to
2432754
Compare
majosm
force-pushed
the
tulio/prod-radiation
branch
from
2432754
to
7017c92
Compare
majosm
reviewed
Mar 27, 2023
Comment on lines
+103
to
+104
| x_plus_y = actx.np.where(actx.np.greater(x + y, 0.0*x), x + y, 0.0*x+1.0) | ||
| return 2.0*x*y/x_plus_y |
There was a problem hiding this comment.
(Coefs are allowed to be integers AFAIK. 🙂)
Comment on lines
+277
to
+334
| class PrescribedFluxDiffusionBoundary(DiffusionBoundary): | ||
| r"""Prescribed flux boundary condition for the diffusion operator. | ||
|
|
||
| For the boundary condition $(\nabla u \cdot \mathbf{\hat{n}})|_\Gamma$, uses | ||
| external data | ||
|
|
||
| .. math:: | ||
|
|
||
| u^+ = u^- | ||
|
|
||
| when computing the boundary fluxes for $\nabla u$, and applies directly | ||
| the prescribed flux when computing $\nabla \cdot (\kappa \nabla u)$. This | ||
| is not the same as prescribing the gradient of $u$. | ||
|
|
||
| .. automethod:: __init__ | ||
| .. automethod:: get_grad_flux | ||
| .. automethod:: get_diffusion_flux | ||
| """ | ||
|
|
||
| def __init__(self, bnd_func): | ||
| """ | ||
| Initialize the boundary condition. | ||
|
|
||
| Parameters | ||
| ---------- | ||
| bnd_func: | ||
| function to prescribe $g$ along the boundary | ||
| """ | ||
| self._function = bnd_func | ||
|
|
||
| def get_grad_flux(self, dcoll, dd_bdry, kappa_minus, u_minus): # noqa: D102 | ||
| actx = u_minus.array_context | ||
| kappa_tpair = TracePair( | ||
| dd_bdry, interior=kappa_minus, exterior=kappa_minus) | ||
| u_tpair = TracePair( | ||
| dd_bdry, interior=u_minus, exterior=u_minus) | ||
| normal = actx.thaw(dcoll.normal(dd_bdry)) | ||
| # XXX using the kappa-weighted average. | ||
| return weighted_grad_facial_flux(kappa_tpair, u_tpair, normal) | ||
|
|
||
| def get_diffusion_flux( | ||
| self, dcoll, dd_bdry, kappa_minus, u_minus, grad_u_minus, | ||
| lengthscales_minus, *, penalty_amount=None, **kwargs): # noqa: D102 | ||
| actx = u_minus.array_context | ||
| normal = actx.thaw(dcoll.normal(dd_bdry)) | ||
| kappa_tpair = TracePair( | ||
| dd_bdry, interior=kappa_minus, exterior=kappa_minus) | ||
| u_tpair = TracePair( | ||
| dd_bdry, interior=u_minus, exterior=u_minus) | ||
| grad_u_tpair = TracePair( | ||
| dd_bdry, interior=grad_u_minus, exterior=grad_u_minus) | ||
| lengthscales_tpair = TracePair( | ||
| dd_bdry, interior=lengthscales_minus, exterior=lengthscales_minus) | ||
| # Note the flipped sign here to match the diffusion notation | ||
| return - self._function(kappa_tpair, u_tpair, grad_u_tpair, | ||
| lengthscales_tpair, normal, penalty_amount, **kwargs) + u_minus*0.0 | ||
|
|
||
|
|
There was a problem hiding this comment.
This isn't being used at the moment, right?
Comment on lines
+140
to
+143
| # FIXME this function is already in "diffusion" | ||
| def _harmonic_mean(actx, x, y): | ||
| x_plus_y = actx.np.where(actx.np.greater(x + y, 0.0*x), x + y, 0.0*x+1.0) | ||
| return 2.0*x*y/x_plus_y |
There was a problem hiding this comment.
Could put this in mirgecom.math, maybe?
Comment on lines
+192
to
+193
| # TODO move this to "diffusion" ??? | ||
| def _diffusion_facial_flux_upwind_with_radiation( |
There was a problem hiding this comment.
Since this is kind of an interface-specific/heat-specific thing (whereas diffusion_operator itself is more physics-agnostic), I think it's probably best to leave this here. We should probably rename it though, since it's not really "upwind" anymore. _diffusion_facial_flux_central_with_radiation?
Comment on lines
+211
to
+220
| # FIXME not entirely sure about this. Need to keep an eye on it... | ||
| # Computing a centered flux "int + ext - radiation" | ||
| # TRR: I disagree about the signs here, but that may be because of the | ||
| # normal orientation... | ||
| flux_on_solid_side = \ | ||
| np.dot(diffusion_flux(kappa_tpair.int, grad_u_tpair.int), normal) | ||
| flux_on_fluid_side = ( | ||
| np.dot(diffusion_flux(kappa_tpair.ext, grad_u_tpair.ext), normal) | ||
| + epsilon_minus * sigma * u_tpair.int**4) | ||
| flux_without_penalty = 0.5*(flux_on_solid_side + flux_on_fluid_side) |
There was a problem hiding this comment.
I think it makes sense for the radiation term to be +, since the normal faces outward.
| mom_bc = self._slip.momentum_bc(cv_minus.momentum, normal) | ||
| t_minus = state_minus.temperature | ||
| t_plus = _project_from_base(dcoll, dd_bdry, self._t_plus) | ||
| t_bc = (t_minus + t_plus)/2.0 # XXX Maybe use t_bc as t_plus? |
There was a problem hiding this comment.
Yeah seems like it would make sense to use t_plus here.
Comment on lines
+758
to
+764
| def grad_temperature_bc(self, dcoll, dd_bdry, gas_model, state_minus, | ||
| grad_cv_minus, grad_t_minus, **kwargs): | ||
| """Get grad(T) on the boundary uses the internal/minus value (aka fluid). | ||
|
|
||
| This is the same logic of an isothermal BC. | ||
| """ | ||
| return _project_from_base(dcoll, dd_bdry, grad_t_minus) |
There was a problem hiding this comment.
I think we can just omit this function like IsothermalWallBoundary does. (PrescribedFluidBoundary defaults to this behavior.)
| dcoll, dd_bdry, kappa_minus, state_minus.temperature) | ||
| t_minus = state_minus.temperature | ||
| t_plus = _project_from_base(dcoll, dd_bdry, self._t_plus) | ||
| t_bc = (t_minus + t_plus)/2.0 # XXX Maybe use t_bc as t_plus? |
There was a problem hiding this comment.
(Same comment as the other instance.)
| kappa_plus = _project_from_base(dcoll, dd_bdry, self.kappa_plus) | ||
| kappa_tpair = TracePair( | ||
| dd_bdry, interior=kappa_minus, exterior=kappa_plus) | ||
|
|
||
| u_plus = _project_from_base(dcoll, dd_bdry, self.u_plus) | ||
| u_tpair = TracePair(dd_bdry, interior=u_minus, exterior=u_plus) | ||
|
|
||
| from mirgecom.diffusion import grad_facial_flux | ||
| return grad_facial_flux(kappa_tpair, u_tpair, normal) | ||
| return average_grad_facial_flux(kappa_tpair, u_tpair, normal) |
There was a problem hiding this comment.
Thinking this should only use kappa_plus/t_plus (or do the 2*t_plus - t_minus thing to achieve the same effect).
| @@ -1429,6 +1431,7 @@ def coupled_ns_heat_operator( | |||
| dcoll, fluid_all_boundaries, fluid_state, quadrature_tag=quadrature_tag, | |||
| dd=fluid_dd, **av_kwargs) | |||
|
|
|||
| # XXX is sigma necessary here? | |||
There was a problem hiding this comment.
I think sigma isn't needed inside diffusion_operator, as it's only used in the boundary (which gets constructed externally and passed in).
|
Superseded by #893. |
Sign up for free
to join this conversation on GitHub.
Already have an account?
Sign in to comment
Add this suggestion to a batch that can be applied as a single commit.
This suggestion is invalid because no changes were made to the code.
Suggestions cannot be applied while the pull request is closed.
Suggestions cannot be applied while viewing a subset of changes.
Only one suggestion per line can be applied in a batch.
Add this suggestion to a batch that can be applied as a single commit.
Applying suggestions on deleted lines is not supported.
You must change the existing code in this line in order to create a valid suggestion.
Outdated suggestions cannot be applied.
This suggestion has been applied or marked resolved.
Suggestions cannot be applied from pending reviews.
Suggestions cannot be applied on multi-line comments.
Suggestions cannot be applied while the pull request is queued to merge.
Suggestion cannot be applied right now. Please check back later.
Not meant for merging.
Questions for the review: