bug in dust-to-gas ratio for multigrain

[markahutch]

The dust-to-gas ratio for the multigrain files is not being computed correctly. Also the gas density in the single-grain one-fluid is different from the gas density in the multigrain one-fluid by a factor of the dust-to-gas ratio.

[danieljprice]

please give specific steps or graphs to show the issue...

[markahutch]

Hi Daniel, More details, as requested... The dust-to-gas ratio is calculated in the extra quantities menu by default in Splash (i.e. it is not dumped by Phantom). Attached is a plot (dust-to-gas_ratio.pdf) comparing the calculated dust-to-gas ratio in a (1) single species one-fluid dump file (black points) and (2) a single species in a multigrain one-fluid dump file with one of the dust fractions set to 0 (blue points). The total dust-to-gas ratio in the Phantom setup is the same in both cases (d2g = 0.00432912085). You can see that the single-phase one-fluid calculated the correct dust-to-gas ratio, but the multigrain does not. Using the same setup as above, you can also see a difference in the gas density between the two cases. Attached is a plot (density.pdf) that compares the gas density. Again, black points show the single-grain one fluid while the blue points show the multigrain with one of the grain sizes having zero dust fraction. The two densities should overlap exactly in this case, but the multigrain is shift upwards by a factor of the dust-to-gas ratio. I have tried this for two different dust-to-gas ratios. I have also verified that using ndusttypes=3 with two grain sizes having zero dust fraction gives the same result as the ndusttypes=2 case. Cheers, Mark

…

On Fri, Nov 9, 2018 at 12:33 AM Daniel Price ***@***.***> wrote: please give specific steps or graphs to show the issue... — You are receiving this because you authored the thread. Reply to this email directly, view it on GitHub <#12 (comment)>, or mute the thread <https://github.com/notifications/unsubscribe-auth/AZrFag6adxo0neo2om2-CMSfSZOdocDnks5utL9AgaJpZM4YUntA> .