Tracking the mass that falls onto the BE sphere

I would like to calculate the mass that falls onto a shell of dr=0.1RBe at r=Rbe from the ambient over the course of a simulation. There may be a few ways to do this, but easiest may be what came to mind today: find M(t) of the sphere with r=1.1Rbe, using Visit's query option for total mass in box.

The method

First, I had to determine the right sum to use in Visit. I see that the 'query' option had 2 sums: weighted and not. Additionally, I found that the sum query is for the current plot. If that plot is a slice of the full simulation, the query will return only a sum of variables from that slice's mesh. Using my knowledge of the BE sphere's total mass from my simulation output —- that is, 151 solar mass, I calculated the mass of the ambient quite easily, given the ambient is of uniform density:

amb = (L^3 - {4\over3} * r^3 * \pi) \rho

Putting this into computational units, I discovered that weighted variable sum was the correct query to get the total rho/cell (and hence mass) in the grid.

The plan was to calculate M(t, 1.1Rbe) using the following formula:

(t, 1.1Rbe) = Mtotal(t)-Mambient(t)

I knew I could query-over-time the Mtotal and perhaps make a clip of the box that would isolate only the ambient, and then query-over-time the Mambient. However, I checked first whether I could just treat Mambient as constant. A movie showing rho(t) of just the ambient indicated I could:

image(ambTimeQuery.png, 35%) image(rhoTimeQueryAmb.gif, 35%)

Considering the Mtot=Mtot(t) as given by Visit's query:

image(timeQueryRho.png, 35%)

I was curious where the change in mass was occurring. Since the density of the ambient, and its volume is staying constant, must be inside of the sphere… Here is a movie of the density inside of the sphere: