Re: A bug in TIMEDEP_ART_VISC (G4)

From: Volker Springel <vspringel_at_MPA-Garching.MPG.DE>
Date: Sat, 15 May 2021 17:06:33 +0200

Dear Yuri,

Thanks very much for pointing this out! You are quite right - this should be fixed now.
(Also the typo in eqn 7)

Best wishes,
Volker

> On 13. May 2021, at 12:02, Yuri Oku <oku_at_astro-osaka.jp> wrote:
>
>
> Dear gadget-list,
>
> I noticed a bug in the calculation of the decay velocity of artificial
> viscosity at line 1030-1033 (and 895-898 for EXPLICIT_VECTRIATION) in
> density.cc when running non-cosmological simulation.
>
> 1030 if(All.ComovingIntegrationOn)
> 1031 vdotr2 += All.cf_atime2_hubble_a * r2;
> 1032
> 1033 double mu_ij = vdotr2 / (All.cf_afac3 * All.Time * kernel.r);
> 1034 double decay_vel;
> 1035
> 1036 if(vdotr2 < 0)
> 1037 decay_vel = targetSphP->Csnd + ngb->Csnd - mu_ij;
> 1038 else
> 1039 decay_vel = targetSphP->Csnd + ngb->Csnd;
>
> At line 1031 and 1033, mu_ij is scaled for comoving integration. For a
> non-cosmological run, this part would be
> mu_ij = vdotr / kernel.r .
>
> Also, there is a typo in the corresponding part of the code paper. In eq. (75),
> v_ij * r_ij
> is
> v_ij * r_ij / |r_ij| .
>
> Best,
> Yuri
>
> --
> Yuri Oku
> Theoretical Astrophysics Group
> Department of Earth and Space Science
> Graduate School of Science, Osaka University, Japan
>
>
>
>
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Received on 2021-05-15 17:06:34

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