Changes between Version 39 and Version 40 of PhysicsDataExplained


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Timestamp:
09/30/14 21:23:47 (10 years ago)
Author:
ehansen
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  • PhysicsDataExplained

    v39 v40  
    2020
    2121 * '''''{{{Xmu:}}}'''''  The mean molecular weight of the gas.  This is sometimes used in conjunction with the mass of a hydrogen atom to determine the number density and temperature scales.  A value of 1.0 is usually used for atomic hydrogen, or 0.5 for molecular hydrogen.
    22 
    23  * '''''{{{MinTemp:}}}'''''  Sets a minimum temperature within the domain.  This should be set to 0.0 if there is no cooling.  If there is cooling, then start by setting it to something low, in the 10^-10^ to 10^-6^ range.  If this parameter is set too high, then it could wind up injecting extra thermal energy into the system.
    24 
    25  * '''''{{{MinDensity:}}}'''''  Sets a minimum density within the domain.  This does not need to be a large value; the default is 10^-30^, and 10^-10^ is most common value in the data files.  Be wary of using large {{{MinDensity}}} values, which can  undermine conservation laws by injecting extra matter into the system. Under no circumstances should {{{MinDensity}}} ever be ''less'' than 0.
    2622
    2723 * '''''{{{InterpOpts:}}}'''''  A multi-integer array that sets the interpolation options for cell-centered variables.  The size of this array is equal to the number of physical variables ({{{NrPhysicalVars}}}).  The interpolation options are actually [http://en.wikipedia.org/wiki/Flux_limiter flux limiters] that prevent spurious numerical oscillations.  The options are as follows:
    … …  
    111107
    112108One other important thing to note...if iCylindrical is not 0, then mydim (a global parameter in physics declarations) will be set to 3, otherwise it is set to ndim. 
     109
     110[[BR]]
     111== Protections ==
     112This section is about the different options that can control density, momentum, and pressure protections.
     113
     114* '''''{{{lRestartOnDensityProtections:}}}'''''  The code will restart the current time step if a density protection is triggered.
     115
     116* '''''{{{lTrackDensityProtections:}}}'''''  A field is added to the q-array to keep track of density protections. Each time a protection is triggered, the cell at that location will increment by 1. This can then be visualized in visit in order to view the "history" of triggered protections throughout your simulation.
     117
     118* '''''{{{iDensityProtect:}}}'''''  Controls how the density is protected.
     119  * {{{0 -- Use MinDensity:}}}  Sets cell density to the {{{MinDensity}}}.
     120  * {{{1 -- Min Nearby Density:}}}  Sets cell density to the minimum density of neighboring cells.
     121  * {{{2 -- Average Nearby Densities:}}}  Sets cell density to average density of neighboring cells.
     122
     123* '''''{{{iMomentumProtect:}}}'''''  Controls how the momentum is protected.
     124  * {{{0 -- Conserve:}}}  Sets cell momentum to value that keeps momentum conserved.
     125  * {{{1 -- Zero:}}}  Sets cell momentum to zero.
     126  * {{{2 -- Average Nearby Velocities:}}}  Sets cell momentum to density x average velocity of neighboring cells.
     127
     128 * '''''{{{MinDensity:}}}'''''  Sets a minimum density within the domain.  This does not need to be a large value; the default is 10^-30^, and 10^-10^ is most common value in the data files.  Be wary of using large {{{MinDensity}}} values, which can  undermine conservation laws by injecting extra matter into the system. Under no circumstances should {{{MinDensity}}} ever be ''less'' than 0.
     129
     130* '''''{{{lRestartOnPressureProtections:}}}'''''  The code will restart the current time step if a pressure protection is triggered.
     131
     132* '''''{{{lTrackPressureProtections:}}}'''''  A field is added to the q-array to keep track of pressure protections. Each time a protection is triggered, the cell at that location will increment by 1. This can then be visualized in visit in order to view the "history" of triggered protections throughout your simulation.
     133
     134* '''''{{{iPressureProtect:}}}'''''  Controls how the pressure is protected.
     135  * {{{0 -- Use MinTemp:}}}  Sets cell temperature to the {{{MinTemp}}}.
     136  * {{{1 -- Min Nearby Pressure:}}}  Sets cell pressure to the minimum pressure of neighboring cells.
     137  * {{{2 -- Average Nearby Pressures:}}}  Sets cell pressure to average pressure of neighboring cells.
     138  * {{{3 -- Min Nearby Temp:}}}  Sets cell temperature to minimum temperature of neighboring cells.
     139  * {{{4 -- Average Nearby Temps:}}}  Sets cell temperature to average temperature of neighboring cells.
     140
     141* '''''{{{MinTemp:}}}'''''  Sets a minimum temperature within the domain. This should be set to 0.0 if there is no cooling.  If there is cooling, then start by setting it to something low, in the 10^-10^ to 10^-6^ range.  If this parameter is set too high, then it could wind up injecting extra thermal energy into the system.