[Users] Oscillations in total angular momentum from QuasiLocalMeasures
Erik Schnetter
schnetter at gmail.com
Sat Mar 23 09:33:47 CDT 2024
Sudipta
Does the oscillation frequency coincide with anything in your
discretization? Is it related to your time step size or to the size of
a grid cell?
What happens if you change the spatial resolution?
-erik
On Thu, Mar 21, 2024 at 8:28 AM Sudipta Hensh <hensh at astro-osaka.jp> wrote:
>
> Hi Erik,
>
> Sorry for the delay, I have written below the answers.
>
> 1. What is the size of the simulation domain?
>
> Simulation domain along x and y direction is [-1000,1000] and along z direction is [0,1000].
>
> 2. At which radius do you evaluate the angular momentum?
>
> There are two extraction radii, 200 and 300. The plot that I sent was for 300.
>
> 3. What is the spatial resolution there?
>
> Spatial resolution is 5.
>
> 4. What is the time resolution there?
>
> The time resolution is 0.75.
>
> 5. Is there any matter nearby?
>
> There is no matter during the inspiral.
>
> 6. What happens if you change the evaluation radius? What if you make it
> smaller or larger?
>
> For smaller radius the amplitude of oscillations is comparatively smaller.
>
> 7. How close is this to the outer boundary?
>
> The extraction radius is far from the outer boundary.
>
> 8. Do you have a visualisation of the geometry (e.g. the imaginary part
> of the Weyl scalar Psi_2)?
>
> I am afraid that I do not have Psi_2 in the output. If necessary then I can output it.
>
> 9. In which direction does the angular momentum point?
> Does this change over time?
>
> The plot I sent was for the angular momentum along z direction.
>
> 10. What is the magnitude of the angular momentum? How does this compare
> to the mass?
>
> The initial magnitude of the angular momentum is 7.3 and total gravitational mass of the system is 2.75 M_Sun.
>
> I am leaving below some information from the parameter file that maybe relevant.
>
> CoordBase::xmin = -1000
> CoordBase::xmax = 1000
> CoordBase::ymin = -1000
> CoordBase::ymax = 1000
> CoordBase::zmin = 0
> CoordBase::zmax = 1000
> CoordBase::spacing = "numcells"
> CoordBase::ncells_x = 200
> CoordBase::ncells_y = 200
> CoordBase::ncells_z = 100
>
> Carpet::max_refinement_levels = 8
> Carpet::time_refinement_factors = "[1,1,2,4,8,16,32,64,128,256,512]"
>
>
> CarpetRegrid2::num_centres = 3
> CarpetRegrid2::regrid_every = 128
> CarpetRegrid2::snap_to_coarse = "yes"
> CarpetRegrid2::freeze_unaligned_levels = "yes"
> CarpetRegrid2::freeze_unaligned_parent_levels = "yes"
>
> # ----------- Region 1 --------------------
> CarpetRegrid2::active_1 = "yes"
> CarpetRegrid2::num_levels_1 = 7
> CarpetRegrid2::position_x_1 = 15.2365094091
> CarpetRegrid2::position_y_1 = 0.0
> CarpetRegrid2::radius_1[1] = 300.0
> CarpetRegrid2::radius_1[2] = 160.0
> CarpetRegrid2::radius_1[3] = 80.0
> CarpetRegrid2::radius_1[4] = 40.0
> CarpetRegrid2::radius_1[5] = 20.0
> CarpetRegrid2::radius_1[6] = 10.0
>
> # ----------- Region 2 --------------------
> CarpetRegrid2::active_2 = "yes"
> CarpetRegrid2::num_levels_2 = 7
> CarpetRegrid2::position_x_2 = -15.2365094091
> CarpetRegrid2::position_y_2 = -0.0
> CarpetRegrid2::radius_2[1] = 300.0
> CarpetRegrid2::radius_2[2] = 160.0
> CarpetRegrid2::radius_2[3] = 80.0
> CarpetRegrid2::radius_2[4] = 40.0
> CarpetRegrid2::radius_2[5] = 20.0
> CarpetRegrid2::radius_2[6] = 10.0
>
> # ----------- Region 3 --------------------
> CarpetRegrid2::active_3 = "yes"
> CarpetRegrid2::num_levels_3 = 3
> CarpetRegrid2::position_x_3 = 0
> CarpetRegrid2::radius_3[1] = 320.0
> CarpetRegrid2::radius_3[2] = 160.0
> CarpetRegrid2::radius_3[3] = 80.0
> CarpetRegrid2::radius_3[4] = 40.0
> CarpetRegrid2::radius_x_3[5] = 30.0
> CarpetRegrid2::radius_y_3[5] = 30.0
> CarpetRegrid2::radius_z_3[5] = 25.0
> CarpetRegrid2::radius_3[6] = 20.0
> CarpetRegrid2::radius_3[7] = 5.0
> # -----------------------------------------
>
> Thanks for your time. I would look forward to hearing from you.
>
> Thanks,
> Sudipta
>
> Sudipta Hensh
> JSPS Postdoctoral Researcher
> Pronouns: He/Him
> Graduate School of Science
> Osaka University
> 1-1 Machikaneyama-cho, Toyonaka
> Osaka 560-0043, Japan
>
> Erik Schnetter wrote:
>
>
> Sudipta
>
> What is the size of the simulation domain?
> At which radius do you evaluate the angular momentum?
> What is the spatial resolution there?
> What is the time resolution there?
> Is there any matter nearby?
> What happens if you change the evaluation radius? What if you make it
> smaller or larger?
> How close is this to the outer boundary?
> Do you have a visualisation of the geometry (e.g. the imaginary part
> of the Weyl scalar Psi_2)?
> In which direction does the angular momentum point?
> Does this change over time?
> What is the magnitude of the angular momentum? How does this compare
> to the mass?
>
> -erik
>
>
> On Tue, Mar 19, 2024 at 9:35 AM Sudipta Hensh <hensh at astro-osaka.jp> wrote:
>
>>
>> Dear all,
>>
>> I hope this email finds you well.
>>
>> I am performing simulations of BNS mergers and utilizing the QuasiLocalMeasures thorn to plot the total angular momentum of the spacetime. However, I have noticed high-frequency oscillations in the plotted data, as shown in the attached plot. I was wondering if we should expect such oscillations. I would also like to know the reason behind such oscillations. I would appreciate if you kindly help me to understand this issue.
>>
>> I am looking forward to hearing from you. Many thanks in advance!
>>
>> Regards,
>> Sudipta Hensh
>> JSPS Postdoctoral Researcher
>> Pronouns: He/Him
>> Graduate School of Science
>> Osaka University
>> 1-1 Machikaneyama-cho, Toyonaka
>> Osaka 560-0043, Japan
>> _______________________________________________
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>>
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>
>
>
> --
> Erik Schnetter <schnetter at gmail.com>
> http://www.perimeterinstitute.ca/personal/eschnetter/
>
>
--
Erik Schnetter <schnetter at gmail.com>
http://www.perimeterinstitute.ca/personal/eschnetter/
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