VisIt

Navigate to the directory containing the chombo*.hdf files you wish to visualize and execute visit (from the command line, visit). From the "Selected files" window in the main GUI, click on a/the listed chombo database and select 'open'.

High resolution datasets can sometimes be arduous to plot. If your dataset is composed of different levels of AMR, you can choose to have visit only plot lower levels of the grid. This can significantly improve computation speed. To do this, go to Controls>Subset. In the first text box, click on levels. You can now un-check levels >0 in the middle text box to turn off higher levels of AMR.

Scripts

Visit supports the use of ​scripts. To execute a script in Visit, go to Controls>Command at the top of the main window. Add the desired script to one of the numbered tabs and execute by clicking on Execute at the bottom left of the Commands window. To save your scripts for later use in Visit, go to Options>Save Settings at the top of the main window.

Below are some helpful scripts to get started. Note that all of them can be modified to suit your preferences.

Opening Chombo Databases

Opening Chombo-format databases can sometimes be confusing when done through the GUI. Instead, one may run the following script to do most of the job.

This script assumes that the files are ch*.hdf files, and that Visit has been invoked with Chombo as the default file format (e.g., visit -default_format Chombo).

(Please NOTE that as is, this script needs some adjustments in order to run smoothly).

# Check to see if a database has already been opened with the script. If one has been, close it.
ns = GetDatabaseNStates()
if ns > 0: 
  DeleteAllPlots()
  CloseDatabase(db)

# Define paths to the data (NOTE: This could probably be done better using dictionaries)
basedir="/home/yirak/"
mydbs=("rtwork/multimode/newstuff/higherres3" \
      ,"rtwork/multimode/newstuff/lowerres3"  \
      ,"clumpyjet/production11"               \
      ,"")
# Concatenate relative paths with basedir
mydbs=[basedir + i for i in mydbs]

# Define the database to be opened ("clumpyjet/production11" in this case)
db=mydbs[2]+"/out/ch*.hdf database"

OpenDatabase(db)

Create Plot With Pre-Set Preferences

This script allows you to have pre-set preferences applied to your databases. Using this script after it has been saved to your Visit settings (see top of script section), is an efficient way of re-applying preferred plot attributes to new data.

# Create a plot and set some preferences...
AddPlot("Pseudocolor","rho")

# Change the frame to the last frame
SetTimeSliderState(TimeSliderGetNStates()-1)

# Set a black background/white foreground
aa = AnnotationAttributes()
aa.backgroundColor = (0, 0, 0, 255)
aa.foregroundColor = (255, 255, 255)

#These colors are customizable. To see the 
#values of other base colors, go to 
#Controls>Annotation>Colors and click on 
#the box which displays a color (either 
#background or foreground color, it doesn't 
#matter) to select the 'More colors...' 
#option. Choose a color, and its Red, Green, 
#and Blue number values will be displayed in
#their given text fields. These numbers you 
#can then copy to the array above, where the 
#values are - (Red, Green, Blue).

SetAnnotationAttributes(aa)
DrawPlots()

Command Line Selection of AMR Levels

As discussed at the top of this page, de-selecting higher levels of AMR can greatly increase the speed at which visit generates plots. Here is a script that switches AMR levels off.

# Assume that the choice is supposed to be for all current plots
np = GetNumPlots()
SetActivePlots(tuple(range(np)))

# Get information about levels
silr = SILRestriction()
silr.SuspendCorrectnessChecking()

# Turn off all levels, in anticipation of turning on only those we want
silr.TurnOffAll()
lvls = silr.SetsInCategory('levels')

# Turn on some level(s)
# 'lvls' has AMR level 0, 1, 2, ...
# stored in lvl[0, 1, 2, ..., -2, -1].
# For example, turn on only the highest level
silr.TurnOnSet(lvls[-1])
silr.EnableCorrectnessChecking()
SetPlotSILRestriction(silr)

# Redraw
DrawPlots()

Average quantities over concentric spherical shells

ActivateDatabase("localhost:/media/grassdata/erica/from_bluehive/FinalRunsNewest/BP/chombo00046.hdf")
filename = "average_vrad_00046.curve"
DeleteActivePlots()
AddPlot("Pseudocolor", "vrad", 1, 1)
SetActivePlots(0)

# inner_sphere():
AddOperator("Clip", 1)
ClipAtts = ClipAttributes()
ClipAtts.quality = ClipAtts.Fast # Fast, Accurate
ClipAtts.funcType = ClipAtts.Sphere # Plane, Sphere
ClipAtts.plane1Status = 1
ClipAtts.plane2Status = 0
ClipAtts.plane3Status = 0
ClipAtts.plane1Origin = (0, 0, 0)
ClipAtts.plane2Origin = (0, 0, 0)
ClipAtts.plane3Origin = (0, 0, 0)
ClipAtts.plane1Normal = (1, 0, 0)
ClipAtts.plane2Normal = (0, 1, 0)
ClipAtts.plane3Normal = (0, 0, 1)
ClipAtts.planeInverse = 0
ClipAtts.planeToolControlledClipPlane = ClipAtts.Plane1 # None, Plane1, Plane2, Plane3
ClipAtts.center = (0, 0, 0)
ClipAtts.radius = 0.06
ClipAtts.sphereInverse = 1
SetOperatorOptions(ClipAtts, 1)
DrawPlots()
f = open(filename, "w")
f.write("# average_vrad\n")
#Query, write average:
Query("Average Value")
t2 = GetQueryOutputValue()
str = "%25.15e %25.15e\n" %(ClipAtts.radius, t2)
f.write(str)
RemoveAllOperators(1)
for i in range(48):
     dx=0.03 #set to be size of smallest cell?
     #inner sphere:
     AddOperator("Clip", 1)
     ClipAtts = ClipAttributes()
     ClipAtts.quality = ClipAtts.Fast # Fast, Accurate
     ClipAtts.funcType = ClipAtts.Sphere # Plane, Sphere
     ClipAtts.plane1Status = 1
     ClipAtts.plane2Status = 0
     ClipAtts.plane3Status = 0
     ClipAtts.plane1Origin = (0, 0, 0)
     ClipAtts.plane2Origin = (0, 0, 0)
     ClipAtts.plane3Origin = (0, 0, 0)
     ClipAtts.plane1Normal = (1, 0, 0)
     ClipAtts.plane2Normal = (0, 1, 0)
     ClipAtts.plane3Normal = (0, 0, 1)
     ClipAtts.planeInverse = 0
     ClipAtts.planeToolControlledClipPlane = ClipAtts.Plane1 # None, Plane1, Plane2, Plane3
     ClipAtts.center = (0, 0, 0)
     ClipAtts.radius = 0.06 + i*dx
     ClipAtts.sphereInverse = 0
     SetOperatorOptions(ClipAtts, 1)
     #Outer-sphere:
     AddOperator("Clip", 1)
     ClipAtts = ClipAttributes()
     ClipAtts.quality = ClipAtts.Fast # Fast, Accurate
     ClipAtts.funcType = ClipAtts.Sphere # Plane, Sphere
     ClipAtts.plane1Status = 1
     ClipAtts.plane2Status = 0
     ClipAtts.plane3Status = 0
     ClipAtts.plane1Origin = (0, 0, 0)
     ClipAtts.plane2Origin = (0, 0, 0)
     ClipAtts.plane3Origin = (0, 0, 0)
     ClipAtts.plane1Normal = (1, 0, 0)
     ClipAtts.plane2Normal = (0, 1, 0)
     ClipAtts.plane3Normal = (0, 0, 1)
     ClipAtts.planeInverse = 0
     ClipAtts.planeToolControlledClipPlane = ClipAtts.Plane1 # None, Plane1, Plane2, Plane3
     ClipAtts.center = (0, 0, 0)
     ClipAtts.radius = 0.06 + (i+1)*dx
     ClipAtts.sphereInverse = 1
     SetOperatorOptions(ClipAtts, 1)
     DrawPlots()
     Query("Average Value")
     t2 = GetQueryOutputValue()
     str = "%25.15e %25.15e\n" %(ClipAtts.radius, t2)
     f.write(str)
     RemoveAllOperators(1)
f.close()
DeleteAllPlots()
OpenDatabase(filename)
AddPlot("Curve", "average_vrad")
DrawPlots()

Create Tiled Image Sequence of Windows Supporting 3D Plot Rotation

#in case you need to restart at a given frame
starting_frame=0

#directory for movie output
my_dir = "/home/jcarroll/astrocub/driven_turb_256/out/Oct11070904"

#base name for movie
movie_name = "Dec64"

#number of rotations around z-axis
rotations=1

#inclination above xy plane in degrees
inclination=30

#initial angle of rotation about z-axis measured from x-axis
phi0=0

#windows to rotate  [1,2,3,...]
windows2rotate = [1]

# ~~~~~~~~~~~~~~~~~  Output file attributes...

OldSaveWindowAtts = SaveWindowAttributes()
SaveWindowAtts = SaveWindowAttributes()
SaveWindowAtts.outputToCurrentDirectory = 0
SaveWindowAtts.outputDirectory = my_dir
SaveWindowAtts.fileName = movie_name 
SaveWindowAtts.family = 0
SaveWindowAtts.format = SaveWindowAtts.JPEG  #BMP, CURVE, JPEG, OBJ, PNG, POSTSCRIPT, PPM, RGB, STL, TIFF, ULTRA, VTK
SaveWindowAtts.maintainAspect = 1
SaveWindowAtts.width = 1024
SaveWindowAtts.height = 1024
SaveWindowAtts.screenCapture = 1  #Need screenCapture = 1 for volume plots to save correctly
SaveWindowAtts.saveTiled = 1
SaveWindowAtts.quality = 80
SaveWindowAtts.progressive = 0
SaveWindowAtts.binary = 0
SaveWindowAtts.stereo = 0
SaveWindowAtts.compression = SaveWindowAtts.PackBits  # None, PackBits, Jpeg, Deflate
GlobalAtts = GetGlobalAttributes()

frames=TimeSliderGetNStates()
from math import *
inclination=inclination*acos(-1)/180
dtheta=2*acos(-1.0)*rotations/frames
phi0=phi0*acos(-1.0)/180

for state in range(starting_frame, frames):
  phi=phi0+state*dtheta
  for wins in GlobalAtts.windows:
    SetActiveWindow(wins)
    SetTimeSliderState(state)
    if wins in windows2rotate:
      c0=GetView3D()
      c0.viewNormal=(cos(inclination)*cos(phi), cos(inclination)*sin(phi),sin(inclination))
      c0.viewUp=(-sin(inclination)*cos(phi), -sin(inclination)*sin(phi), cos(inclination))
      SetView3D(c0)
  SaveWindowAtts.fileName = movie_name + "%(frame)04d" % {'frame':state}
  SetSaveWindowAttributes(SaveWindowAtts)
  SaveWindow()

SetSaveWindowAttributes(OldSaveWindowAtts)

Same as Above With Time Slider State Query and Time-Scale Variable Printing

Note that in this script, any text object created will show up in the Controls>Annotation Menu under Objects. You can delete them if you need to start over again

#in case you need to restart at a given frame
starting_frame=1

#directory for movie output
my_dir = "/home/chaig/envelope21_2/"

#base name for movie
movie_name = "envelope21_2_density_mach"

#time scaling, if any:
timesc1 = 1.40796638173  # for analytic disk 3 AU rotational time
timesc5 = 0.497791288101  # for analytic disk 3 AU free-fall time
timesc10 = 164660183.697  # Runtimesc for lscale = 1 AU 


#number of rotations around z-axis
#rotations=.5

#inclination above xy plane in degrees
#inclination=30

#initial angle of rotation about z-axis measured from x-axis
#phi0=0

#windows to rotate
#windows2rotate = [1]

#~~~~~~~~~~~~~~~~~ Output Annotation Attributes
AnnotationAtts = GetAnnotationAttributes()


# ~~~~~~~~~~~~~~~~~  Output file attributes...

OldSaveWindowAtts = SaveWindowAttributes()
SaveWindowAtts = SaveWindowAttributes()
SaveWindowAtts.outputToCurrentDirectory = 0
SaveWindowAtts.outputDirectory = my_dir
SaveWindowAtts.fileName = movie_name 
SaveWindowAtts.family = 0
SaveWindowAtts.format = SaveWindowAtts.PNG  #BMP, CURVE, JPEG, OBJ, PNG, POSTSCRIPT, PPM, RGB, STL, TIFF, ULTRA, VTK
#SaveWindowAtts.maintainAspect = 1
SaveWindowAtts.width = 1024
SaveWindowAtts.height = 1024
SaveWindowAtts.screenCapture = 1
SaveWindowAtts.saveTiled = 1
SaveWindowAtts.quality = 80
SaveWindowAtts.progressive = 0
SaveWindowAtts.binary = 0
SaveWindowAtts.stereo = 0
SaveWindowAtts.compression = SaveWindowAtts.PackBits  # None, PackBits, Jpeg, Deflate
GlobalAtts = GetGlobalAttributes()

frames=TimeSliderGetNStates()
#from math import *
#inclination=inclination*acos(-1)/180
#dtheta=2*acos(-1.0)*rotations/frames
#phi0=phi0*acos(-1.0)/180

slider = CreateAnnotationObject("Text2D")  # This creates a text object
slider.width = 0.3                         # This sets the width of the object
slider.SetPosition(0.6, 0.57)              # This sets the position on the screen of the object
slider.useForegroundForTextColor = 0       # If you wish the text be simply black, set this to 1
slider.textColor = (0,0,0,255)             # RGBT color - T for transparency


for state in range(0, frames):
#  phi=phi0+state*dtheta
  for wins in GlobalAtts.windows:
    SetActiveWindow(wins)
    SetTimeSliderState(state)
#    if wins in windows2rotate:
#      c0=GetView3D()
#      c0.viewNormal=(cos(inclination)*cos(phi), cos(inclination)*sin(phi),sin(inclination))
#      c0.viewUp=(-sin(inclination)*cos(phi), -sin(inclination)*sin(phi), cos(inclination))
#      SetView3D(c0)

# Query the value of the time slider state
  Query("Time")                   
  v = GetQueryOutputValue()/timesc1
  f = GetQueryOutputValue()/timesc5
  j = GetQueryOutputValue()*timesc10
  k = GetQueryOutputValue()*timesc10/(31556736)

# Add what you wish to your string - %g indicates that a variable is coming to the right of the "
  string =  "Orbits at 3 AU = %g" %v
  string = string + "\n Free Fall Times from 3 AU = %g" %f
  string = string + "\n Time (seconds) = %g" %j
  string = string + "\n Time (years) = %g" %k
  string = string + "\n density scale = 1e8 cm-3"
  string = string + "\n Run Time Scaling = %g" %k

# Set the string to be the slider text
  slider.text = string

  SaveWindowAtts.fileName = movie_name + "%(frame)04d" % {'frame':state}
  SetSaveWindowAttributes(SaveWindowAtts)
  SaveWindow()

SetSaveWindowAttributes(OldSaveWindowAtts)

Script for following collapse of uniform sphere

This script adjusts the window bounds to zoom in on a region at the same rate the region collapses (assuming it follows the solution for a uniform density sphere undergoing free fall collapse)

r_0=60                 # Initial radius of view (usually 150% of clump radius is good)
r_min=8                # Radius to stop shrinking at (32*levels(MaxLevel)%dx)
singular_time=.66      #t_ff using clump density in computational units (or by eye)
center=(240,240)       #Clump location in computational units
starting_frame=0       #Frame to start from
final_frame=63         #Frame to stop at
my_dir = "/grassdata/johannjc/scrambler_111007/modules/Problem/Images/2D" #directory for movie output
movie_name = "ZoomingRhoTestwSinksA" #base name for movie


# ~~~~~~~~~~~~~~~~~  Output file attributes...  ~~~~~~~~~~~~~~~~~~~~~~~~~
OldSaveWindowAtts = SaveWindowAttributes()
SaveWindowAtts = SaveWindowAttributes()
SaveWindowAtts.outputToCurrentDirectory = 0
SaveWindowAtts.outputDirectory = my_dir
SaveWindowAtts.fileName = movie_name 
SaveWindowAtts.family = 0
SaveWindowAtts.format = SaveWindowAtts.PNG  #BMP, CURVE, JPEG, OBJ, PNG, POSTSCRIPT, PPM, RGB, STL, TIFF, ULTRA, VTK
SaveWindowAtts.width = 1024
SaveWindowAtts.height = 1024
SaveWindowAtts.screenCapture = 1
SaveWindowAtts.saveTiled = 1
SaveWindowAtts.quality = 80
SaveWindowAtts.progressive = 0
SaveWindowAtts.binary = 0
SaveWindowAtts.stereo = 0
SaveWindowAtts.compression = SaveWindowAtts.PackBits
GlobalAtts = GetGlobalAttributes()


a=GetView2D()
from math import *
for state in range(starting_frame, final_frame):
  Query('Time')   #Get current database time
  tratio=min(GetQueryOutputValue()/singular_time*1.0,1.0) # Calculate t/t_ff
  rratio=.7178*sqrt(1-tratio**2)+.3068*(1-tratio**2)-.01842 # Approximate fit to free fall radius ratio
  r=max(r_min,r_0*rratio) # Scale current radius based on rratio keeping it > r_min
  a.windowCoords=(center[0]-r, center[0]+r, center[1]-r, center[1]+r) # Set window coords to encompass clump circle
  for wins in GlobalAtts.windows: #In case there are multiple windows
    SetActiveWindow(wins)
    SetTimeSliderState(state)
    SetView2D(a)
  SaveWindowAtts.fileName = movie_name + "%(frame)04d" % {'frame':state}
  SetSaveWindowAttributes(SaveWindowAtts)
  SaveWindow()
  ClearCache("localhost")
SetSaveWindowAttributes(OldSaveWindowAtts)

More complicated movie tracking a particle

I first had to use some linux-fu to get the particle's xy location that I wanted to track into xloc.dat. I then used d=f.readline to read each line and c=d.split to parse the line. I then used c[3] and c[5] as the x and y position of the particle which I then used to set the window coords etc… Here is an AVI version of the movie​

movie_name="sinkzoom"
framestart_mesh=130
framestart_zoom=160
frameend_zoom=190
frameadd_v=220
frameend=300
zoom_factor=12
zf=zoom_factor**(1.0/(frameend_zoom-framestart_zoom))
print zf
f=open('xloc.dat')
SaveWindowAtts = SaveWindowAttributes()
SaveWindowAtts.fileName = movie_name
SaveWindowAtts.family = 0
for i in range(0,framestart_mesh):
  f.readline()
  SetTimeSliderState(i)
  SaveWindowAtts.fileName = movie_name + "%(frame)04d" % {'frame':i}
  SetSaveWindowAttributes(SaveWindowAtts)
  SaveWindow()
  ClearCache("localhost")
a=GetView2D()
b=GetView2D()
AddPlot("Mesh","Mesh")
DrawPlots()
for i in range(framestart_mesh, framestart_zoom):
  f.readline()
  SetTimeSliderState(i)
  SaveWindowAtts.fileName = movie_name + "%(frame)04d" % {'frame':i}
  SetSaveWindowAttributes(SaveWindowAtts)
  SaveWindow()
  ClearCache("localhost")
for i in range(framestart_zoom, frameend_zoom):
  d=f.readline()
  c=d.split()
  x=float(c[3])
  y=float(c[5])
  print x,y
  viewsizex=(b.windowCoords[1]-b.windowCoords[0])/(zf**(i-framestart_zoom+1))
  viewsizey=(b.windowCoords[3]-b.windowCoords[2])/(zf**(i-framestart_zoom+1))
  xlower = max(b.windowCoords[0], x-viewsizex/2)
  ylower = max(b.windowCoords[2], y-viewsizey/2)
  xupper = min(b.windowCoords[1], xlower+viewsizex)
  yupper=min(b.windowCoords[3], ylower+viewsizey)
  xlower=xupper-viewsizex
  ylower=yupper-viewsizey
  a.windowCoords=(xlower,xupper,ylower,yupper)
  SetView2D(a)
  SetTimeSliderState(i)
  SaveWindowAtts.fileName = movie_name + "%(frame)04d" % {'frame':i}
  SetSaveWindowAttributes(SaveWindowAtts)
  SaveWindow()
  ClearCache("localhost")
SetActivePlots(2)
HideActivePlots()
for i in range (frameend_zoom,frameadd_v):
  d=f.readline()
  c=d.split()
  x=float(c[3])
  y=float(c[5])
  print x,y
  viewsizex=(b.windowCoords[1]-b.windowCoords[0])/zoom_factor
  viewsizey=(b.windowCoords[3]-b.windowCoords[2])/zoom_factor
  xlower = max(b.windowCoords[0], x-viewsizex/2)
  ylower = max(b.windowCoords[2], y-viewsizey/2)
  xupper = min(b.windowCoords[1], xlower+viewsizex)
  yupper=min(b.windowCoords[3], ylower+viewsizey)
  xlower=xupper-viewsizex
  ylower=yupper-viewsizey
  a.windowCoords=(xlower,xupper,ylower,yupper)
  SetView2D(a)
  SetTimeSliderState(i)
  SaveWindowAtts.fileName = movie_name + "%(frame)04d" % {'frame':i}
  SetSaveWindowAttributes(SaveWindowAtts)
  SaveWindow()
  ClearCache("localhost")
AddPlot("Vector","v")
DrawPlots()
for i in range (frameadd_v,frameend):
  d=f.readline()
  c=d.split()
  x=float(c[3])
  y=float(c[5])
  print x,y
  viewsizex=(b.windowCoords[1]-b.windowCoords[0])/zoom_factor
  viewsizey=(b.windowCoords[3]-b.windowCoords[2])/zoom_factor
  xlower = max(b.windowCoords[0], x-viewsizex/2)
  ylower = max(b.windowCoords[2], y-viewsizey/2)
  xupper = min(b.windowCoords[1], xlower+viewsizex)
  yupper=min(b.windowCoords[3], ylower+viewsizey)
  xlower=xupper-viewsizex
  ylower=yupper-viewsizey
  a.windowCoords=(xlower,xupper,ylower,yupper)
  SetView2D(a)
  SetTimeSliderState(i)
  SaveWindowAtts.fileName = movie_name + "%(frame)04d" % {'frame':i}
  SetSaveWindowAttributes(SaveWindowAtts)
  SaveWindow()
  ClearCache("localhost")
f.close()

Derived Expressions

Using Controls>Expressions, Visit users can create derived expressions based on the components in the Chombo (or BOV) files and the mesh. Refer to ​What data file formats can VisIt read? for a description of these file formats.

Users can visualize their expressions by choosing the desired plot type from Plots and then selecting the desired expression; i.e., Plots>Pseudocolor>Expression_Name.

Chombo Expressions

Some standard expressions for chombo files are given below. Note that a forward slash will create a subdirectory of variables.

Expressions can be specified in terms of scalar variables or vector variables. Make sure when defining an expression that uses vectors, 'Vector Mesh Variable' is set on the "type" drop-down menu in the Expressions window. Vector expressions are identified as such in the table below.

(Note that these expressions are displayed with sub- and superscripts. You should be aware of this if you attempt to copy and paste them straight into VisIt, which accepts only plain text.)

Chombo Expressions
Name	Definition	Expression	Notes
vx	px/rho	velocity in x
vy	py/rho	velocity in y
vz	pz/rho	velocity in z
2d/vmag	sqrt(vx^2+vy^2)	magnitude of velocity in 2-d
3d/vmag	sqrt(vx^2+vy^2+vz^2)	magnitude of velocity in 3-d
gamma	5/3
hydro/2dpressure	(gamma-1)*(E-0.5*(px^2+py^2)/rho)	Hydro pressure, 2d
hydro/3dpressure	(gamma-1)*(E-0.5*(px^2+py^2+pz^2)/rho)	Hydro pressure, 3d
hydro/Temp	<hydro/pressure>/rho	temperature for hydro	note use of another derived expression
hydro/TempPhysical	tempScale*<hydro/pressure>/rho	Gives T in physical units	tempScale should be defined in physics.data
MHD/pressure	(gamma-1)*(E-0.5*(px^2+py^2+pz^2)/rho-0.5*(Bx^2+By^2+Bz^2))	MHD pressure	Includes magnetic terms!
MHD/Bmag	sqrt(Bx^2+By^2[+ Bz^2])	MHD Plasma Beta	Bracketed term is optional, depending on if you are in 2d or 3d
MHD/invbeta	<MHD/Bmag>^2/<MHD/pressure>	MHD Inverse Plasma Beta
MHD/Temp	<MHD/pressure>/rho	temperature for MHD
MHD/TempPhysical	tempScale*<MHD/pressure>/rho
2d/soundSpeed	sqrt((5/3) * <hydro/pressure> * rho^-1)	sound speed, 2D	assumes gamma = 5/3, if using MHD this expression should use MHD pressure
3d/soundSpeed	sqrt((5/3) * <hydro/pressure> * rho^-1)	sound speed, 3D	assumes gamma = 5/3, and above comment applies here as well
2d/Mach	<2d/vmag> / <2d/soundSpeed>	Mach number
3d/Mach	<3d/vmag> / <3d/soundSpeed>	Mach number, 3D
Bvec	{Bx,By}	Magnetic field lines	! vector mesh quantity
2d/divB	divergence(Bvec)	divergence of magnetic field, 2D
Vvec	{vx,vy}	velocity vector field	! vector mesh quantity
2d/divV	divergence(Vvec)	divergence of vector field, 2D
2d/vort	curl(Vvec)	vorticity, 2D	! As this is a plot of a 2d expression, it must be chosen as a scaler variable
2d/gradVel	magnitude(gradient(<2d/vmag>))	magnitude of gradient of velocity
schlieren	magnitude(gradient(log10(rho)))	synthetic Schlieren image
3d/entropy	log10(<hydro/3dpressure>)-(gamma)*log10(rho)	entropy, 3D
misc/position_vec	coord(Mesh)	position vector	! vector mesh variable
misc/position_mag	magnitude(coord(Mesh))	scalar position
misc/position_proj	magnitude({cos(deg2rad(30.))*position_vec![0], sin(deg2rad(30.))*position_vec![1]})	position projected at 30 degrees	note first component of pos_vec is at 0
misc/proj_vx	cos(deg2rad(30.))*px*rho^-1	vx projected at 30 degrees
hydro-static equilibrium	magnitude(gradient(pressure)/rho) + magnitude(gradient (Phi))		Scaler force equation.

BOV expressions

The variables in the BOV files from AstroCub are in different order than in AstroBear. Here are some equivalent expressions:

BOV Expressions
Name	Definition	Expression	Notes
comp/vx	comp02*comp00^-1	x-velocity
comp/vy	comp03*comp00^-1	y-velocity
comp/2dpressure	(5/3-1)*(comp01-0.5*(comp02+comp03 )*comp00)	pressure, 2D	assumes gamma = 5/3
comp/2dTemp	<comp/p>*comp00^-1	temperature, 2D