[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
>> _______________________________________________
>> Users mailing list
>> Users at einsteintoolkit.org
>>
> http://lists.einsteintoolkit.org/mailman/listinfo/users
>
>
>
> --
> Erik Schnetter <schnetter at gmail.com>
> http://www.perimeterinstitute.ca/personal/eschnetter/
>
>


-- 
Erik Schnetter <schnetter at gmail.com>
http://www.perimeterinstitute.ca/personal/eschnetter/


More information about the Users mailing list