Noisy solves an advection-diffusion-decay equation that is forced by a noise model. Generates a gaussian random field.
Model parameters are set in noisy.h.
Output is a series of ppm files in subdirectory images, and an
ascii snapshot of the final state in noisy.out.
Two models are currently available. Choose a model by editing
makefile.
model_uniform.c has constant advection velocity, set to 0 by default.
anisotropic diffusion, unit decay time, and a constant-in-time
white-noise forcing. This converges quickly to a steady-state
solution of the diffusion-decay equation. This model is useful
for testing the code.
model_disk.c mocks up an accretion disk on the sky. Diffusion
coefficients decay time, and orientation of the diffusion tensor
are all space dependent. Forcing is white noise in space and time.
Follows Lee & Gammie 2020, based on Lindgren, Rue, and Lindstrom 2011 J.R. Statist. Soc. B 73, pp 423-498.
In particular, noisy implements eq. 17, which has power spectrum given by eq. 18.
4 Jan 2020