Re: gas smoothing length options

From: David Riethmiller <>
Date: Tue, 27 Mar 2012 19:10:57 -0400

Hi Nathan -

I think I asked the question incorrectly. I want to specify the SPH
smoothing length for every particle myself, and not have Gadget
compute it. I'm not referring to the gravitational softening length,
but rather to the kernel size. According to the Gadget manual
(section 6.4), "gas densities, SPH smoothing lengths, and all further
blocks need not be provided." What I'm asking is, what if I DO want
to specify further blocks, namely the densities and SPH smoothing


On Mar 27, 2012, at 6:19 PM, Nathan Goldbaum wrote:

> Hi David,
> As far as I know the gas smoothing lengths are already adaptive in
> Gadget-2. The smoothing lengths are calculated at runtime based on
> the DesNumNgb parameter so it's not necessary to read them in from
> an input file. The minimum smoothing length is set by the parameter
> MinGasHsmlFractional which can be equal to zero if you want to allow
> the SPH smoothing length to go to zero for dense particle groupings.
> The gravitational smoothing lengths for SPH particles can be set
> equal to their SPH smoothing lengths by turning on
> Nathan Goldbaum
> Graduate Student
> Astronomy & Astrophysics, UCSC
> On Mar 27, 2012, at 3:09 PM, David Riethmiller wrote:
>> Hi Gadget users -
>> Has anyone enabled a variable smoothing length option for gas
>> particles? I'd like to relax the requirement that all type 0
>> particles have the same smoothing length as set in the control
>> file, and instead include HSML in the list of attributes read in
>> from the initial conditions. I'm about to start editing read_ic.c;
>> am I on the right path?
>> Thanks,
>> Dave
>> -------------------------------------------------
>> David A. Riethmiller
>> Ph.D. Candidate, Astrophysical Institute
>> Ohio University
>> Clippinger Labs 338
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David A. Riethmiller
Ph.D. Candidate, Astrophysical Institute
Ohio University

Clippinger Labs 338
Received on 2012-03-28 01:11:07

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