[FLASH-USERS] a problem in the unit of active particles

[Congyao Zhang]

Hello everyone,

I have a question about  the unit of active particles (massive and
cosmological). In the user-guide, the equation shown in the part
"Cosmological variable-timestep leapfrog" shows that "A= -2 *  a_dot / a",
where a is the scale factor.

I copy the source code below (from the file
"pt_advancLeapfrog_cosmos.F90"),

  alpha    = 2*Hubble/sOld * sqrt(OmegaM/sOld-OmegaCurv+OmegaL*sOld**2)
  dotalpha = 2*Hubble**2 * (-3*OmegaM + 2*OmegaCurv*sOld)/sOld**3

1. there is a "sign" difference between the equation in the user-guide and
the code.
2. there seems an additional factor of 2 in dotalpha. It should be
"dotalpha = Hubble**2 * (-3*OmegaM + 2*OmegaCurv*sOld)/sOld**3". Am I
correct?

Thank you for your time!

Best regards,
Congyao
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://flash.rochester.edu/pipermail/flash-users/attachments/20190321/dc3d4817/attachment.htm>