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timeDependentVhgr

Description

The timeDependentVhgr class in OFFBEAT allows you to set a average volumetric heat generation rate (vhgr) in unit of W/m3. Similar to timeDependentVhgr, this class allow users to provide time-dependent vhgr. Since this class is mainly developed for TRISO, it currently doesn't support the addition of a radial and an axial profile of vhgr (as done in the lhgr heat source classes).

Options

The timeDependentVhgr heat source model requires the user to specify a few additional parameters in the heatSourceOptions sub-dictionary located within the solverDict.

Parameters in heatSourceOptions:

timePoints A list of time values at which the vhgr is provided. The time unit depend on the userTime selected by the user (seconds by default).
vhgr A list of vhgr values in W/m3, one value per time-point.
timeInterpolationMethod Select the time interpolation method for time steps that fall in between the time points indicated in the timePoints list.
materials A list of material (or cellZones names) where the heat source model applies.

Usage

Here is a code snippet of the solverDict to be used for the case of a vhgr that ramps to 1e9 W/m3 in 1hr time, remains constant for a year, and then ramps down to 0 in 1 hr.

heatSource timeDependentVhgr;

heatSourceOptions
{
    //           t0  1hr    1yr       1yr+1hr
    timePoints  ( 0   3600 31536000  31539600);
    vhgr        ( 0   1e9  1e9       0       );

    timeInterpolationMethod linear; //step;

    materials ( fuel );
}

As the time point or data lists might be quite long for a realistic history, making the solver dictionary less readable, the user can create separate files and include them in the heatSourceOptions dictionary using the #include command. E.g.:

heatSourceOptions
{
    timePoints  #include "$FOAM_CASE/constant/lists/timePoints";
    lhgr        #include "$FOAM_CASE/constant/lists/avgPower";
    timeInterpolationMethod linear;

    ...
}