[aspect-devel] S40RTS and thermal boundary layers

Fri Jul 22 15:31:23 PDT 2016

Yes, they do vanish when I remove the 'Fixed temperature boundary indicators'
parameter as suggested by Rene... but I guess I'm trying to wrap my head
around how the ASPECT code takes those initial conditions and fixed
temperatures and generates "boundary layers" in a single time step? (I'll
include a picture of both versions for clarity.)

Fortunately, this doesn't have an impact on the dynamic topography or
instantaneous flow, but I would like to understand all the same.

Thanks a lot for letting me know about the update to S40RTS!

Marie

On Fri, Jul 22, 2016 at 11:28 AM, Austermann, Jacqueline <
jaustermann at fas.harvard.edu> wrote:

> Hi Marie,
>
> Just to chime in on this, my first thought is the same as Rene’s: I would
> think that you see "boundary layers" because you prescribe an inner and
> outer temperature that is very different from the adiabatic reference
> temperature within the mantle (and the S40RTS perturbations are very small
> compared to those boundary layer jumps). To check whether that’s the case
> you can look at the output and / or not impose these temperature boundary
> conditions … i.e. exactly what Rene said. S40RTS does not include boundary
> layers in itself, it’s only a perturbation to the depth dependent
> temperature profile. I also wanted to add that Shangxin fixed a bug in the
> normalization of the S40RTS initial condition during the hackathon so it
> might be worth updating your branch to the newest developer version of
> aspect.
>
> Best,
> Jacky
>
>
>
>
> On Jul 22, 2016, at 12:47 AM, Rene Gassmoeller <
> rene.gassmoeller at mailbox.org> wrote:
>
> Hi Marie,
>
> as far as I can see the S40RTS perturbation should not impose boundary
> layers, unless there are some in S40RTS itself (but I suppose they are
> subtracted from the tomography model, i.e. it is defined by subtracting a
> lateral average?). Jacky and Shangxin have more experience with that, maybe
> they have more insight? Another reason might be that you are prescribing
> boundary temperatures at the top and bottom, which will overlap with the
> initial condition in the outermost/innermost cells. Do you see these
> boundary layers also in elements below the outermost shell? Do you see them
> if you remove 'inner' and 'outer' from the 'Fixed temperature boundary
> indicators'?
> Best,
> Rene
>
>
> On 07/21/2016 11:28 AM, Marie Kajan wrote:
>
> Hey all,
>
> Quick question. I'm not sure if this is specific to how ASPECT works or
> just my chosen parameters, but I'm using the S40RTS perturbation with the
> simple compressible material model and can already see boundary layers in
> my temperature profile at the first time step. Can anyone tell me where
> these come from? Are they imposed by ASPECT due to my temperature boundary
> conditions, and how?
>
> I'll paste my parameter file minus output settings below. Thanks!
>
> Marie
>
> ---
>
> set Dimension                              = 3
> set Start time                             = 0
> set End time                               = 0
> set Linear solver tolerance                = 1e-5
> set Max nonlinear iterations               = 100
> set Nonlinear solver scheme                = iterated IMPES
> set Nonlinear solver tolerance             = 1e-5
> set Number of cheap Stokes solver steps    = 0
> set Output directory                       =
> /RQexec/mnk/aspect/output_shell_simple_3d_freeslip_s40rts_compressible
> set Use years in output instead of seconds = true
>
>
> subsection Boundary temperature model
>   set Model name = spherical constant
>
>   subsection Spherical constant
>     set Inner temperature = 4000
>     set Outer temperature = 300
>   end
> end
>
>
> subsection Discretization
>   set Use locally conservative discretization = false
>
>   subsection Stabilization parameters
>     set alpha = 2
>     set beta  = 0.117
>     set cR    = 0.5
>   end
> end
>
>
> subsection Geometry model
>    set Model name = spherical shell
>
>   subsection Spherical shell
>     set Inner radius = 3481000
>     set Outer radius = 6371000
>   end
> end
>
>
> subsection Gravity model
>   set Model name = radial earth-like
> end
>
>
> subsection Heating model
>   set List of model names = adiabatic heating
>
>   subsection Adiabatic heating
>     set Use simplified adiabatic heating = true
>   end
> end
>
>
> subsection Initial conditions
>   set Model name = S40RTS perturbation
>
>   subsection S40RTS perturbation
>     set Data directory                                               =
> /home/mnk/aspect-1.4.0/data/initial-conditions/S40RTS/
>     set Initial condition file name                                  =
> S40RTS.sph
>     set Remove degree 0 from perturbation                            = true
>     set Spline knots depth file name                                 =
> Spline_knots.txt
>     set Thermal expansion coefficient in initial temperature scaling = 3e-5
>     set Vs to density scaling                                        = 0.2
>   end
> end
>
>
> subsection Material model
>   set Model name = simple compressible
> end
>
>
> subsection Mesh refinement
>   set Initial adaptive refinement = 0
>   set Initial global refinement   = 4
> end
>
>
> subsection Model settings
>   set Fixed temperature boundary indicators   = inner, outer
>   set Tangential velocity boundary indicators = inner, outer
>   set Remove nullspace                        = net rotation
> end
>
>
> _______________________________________________
> Aspect-devel mailing listAspect-devel at geodynamics.orghttp://lists.geodynamics.org/cgi-bin/mailman/listinfo/aspect-devel <https://urldefense.proofpoint.com/v2/url?u=http-3A__lists.geodynamics.org_cgi-2Dbin_mailman_listinfo_aspect-2Ddevel&d=CwMDaQ&c=WO-RGvefibhHBZq3fL85hQ&r=j5AqZvMsoErn2L-vpbdTErPRtyT4BhzQUwKzsenbbTc&m=sjBZyYoO5Rc5jH55r1G9b46ZqxLERo773tYDSTiiR2w&s=WfwIg6I89KhzD3uQzMZMFpD75cz7HEb1Y_nys_4QMlA&e=>
>
>
> _______________________________________________
> Aspect-devel mailing list
> Aspect-devel at geodynamics.org
> http://lists.geodynamics.org/cgi-bin/mailman/listinfo/aspect-devel
>
>
>
> _______________________________________________
> Aspect-devel mailing list
> Aspect-devel at geodynamics.org
> http://lists.geodynamics.org/cgi-bin/mailman/listinfo/aspect-devel
>
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://lists.geodynamics.org/pipermail/aspect-devel/attachments/20160722/5e31b44a/attachment-0001.html>
-------------- next part --------------
A non-text attachment was scrubbed...
Name: simple_compressible_s40rts.png
Type: image/png
Size: 4280 bytes
Desc: not available
URL: <http://lists.geodynamics.org/pipermail/aspect-devel/attachments/20160722/5e31b44a/attachment-0002.png>
-------------- next part --------------
A non-text attachment was scrubbed...
Name: simple_compressible_s40rts_noBCs.png
Type: image/png
Size: 4868 bytes
Desc: not available
URL: <http://lists.geodynamics.org/pipermail/aspect-devel/attachments/20160722/5e31b44a/attachment-0003.png>