[Mesa-users] taking very small steps during accretion

[Wolf, William M]

Hi Harish,

It looks like in your inlist, you have mass_change = 1.5d6. I advise that instead of just turning on the mass change full blast, you ramp it over time. In particular, I’d look at the relax_mass_change controls, which let you change the value of mass_change over time.

However, with such a high accretion rate, you might have to do this in steps, as this control increases the accretion rate linearly. That is, if you ramp things up from 0 to 1.5d-6 over 100 timesteps, the very first timestep will abruptly turn on accretion at 1.5d-8 Msun/yr, which may also be too fast. Perhaps first adjust it to 1d-8, save a model, and then adjust it again to your final accretion rate. If the model you are loading was already accreting matter, you may be able to be more aggressive and do this in one relaxation.

Good luck!

Regards,

Bill Wolf

From: Mesa-users <mesa-users-bounces at lists.mesastar.org> on behalf of harish sorrout via Mesa-users <mesa-users at lists.mesastar.org>
Date: Monday, August 16, 2021 at 6:09 AM
To: Mesa-users <mesa-users at lists.mesastar.org>
Subject: [Mesa-users] taking very small steps during accretion
Respected sir,

I am performing a simulation of long term evolution of WD accreting matter with accretion rate 1d-6 on my laptop with 4 threads and 16 GB ram. It is taking very small time steps and to increase time steps I have done many things like change mesh_coeff, var_control but I have failed to increase the time steps and I have run it more than 3-4 days. I wanted to achieve the Chandrasekhar limit of WD but it looks very different with this time step . because it will take 20 to 25 days to achieve ch mass limit. Here I am sharing an inlist file and TRHO plot.

kindly help me where am i wrong. and how can i achieve the target.

Thanking you

with regards
Harish kumar
research scholar
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