diff --git a/doc/ReleaseNotes/develop.tex b/doc/ReleaseNotes/develop.tex index a270ee900b7..7e1a6439ae0 100644 --- a/doc/ReleaseNotes/develop.tex +++ b/doc/ReleaseNotes/develop.tex @@ -49,8 +49,8 @@ \item When the SQUARE\_GWET option was invoked in the UZF options block, evapotranspiration from the water table (GWET) was calculated incorrectly. Instead of acting as a sink, the calculated evapotranspiration flux was added as a source of water. The applied fix ensures that groundwater evapotranspiration is removed from the water table and as a result the GWET values are accumulated as outflows in the budget table. \item The number of characters used to represent integers and floating point numbers in MODFLOW input files was restricted to 30. The program was modified to accept any number of characters provided the number is valid. This may be useful for parameter estimation programs that use character substitution to create new input files. \item A string to character array conversion function in the BMI interface could fail on Apple silicon macOS with recent versions of GNU Fortran, producing array extent errors at runtime. This has been fixed by properly specifying the intent of a dummy argument in the relevant function. - \item With a flow model using the Newton formulation, the PRT model could crash upon a particle's entry into a dry cell. This has been fixed. - \item With a flow model using the Newton formulation, the PRT model could enter an endless loop upon a particle's entry to a dry cell if that cell contains a boundary package (e.g. a pumping well). Where the particle should be captured and terminate, it would instead be passed back and forth between the cell bottom and the top of the cell below. To avoid this, particles are forbidden from backtracking (reentering the previous cell) within the same time step. + \item With a GWF model using the Newton formulation, the PRT model could crash upon a particle's entry into a dry cell. This has been fixed. + \item With a GWF model using the Newton formulation, the PRT model could enter an endless loop upon a particle's entry to a dry cell if that cell contains a boundary package (e.g. a pumping well). Where the particle should be captured and terminate, it would instead be passed back and forth between the cell bottom and the top of the cell below. To avoid this, particles are forbidden from backtracking (reentering the previous cell) within the same time step. \item The PRT model now allows more control over vertical particle motion in dry conditions. In addition to the existing DRAPE option, which controls release-time behavior, the PRP package now provides a DRY\_TRACKING\_METHOD option which configures how dry particles (particles in dry cells, or above the water table in partially saturated cells) behave at tracking time. This option is relevant only when the Newton formulation is used, in which case dry cells remain active; otherwise, dry cells are inactive and particles will terminate. See the MF6IO document for a detailed explanation of DRY\_TRACKING\_METHOD. \end{itemize} diff --git a/doc/mf6io/prt/prt.tex b/doc/mf6io/prt/prt.tex index bde9e3a82ae..07310ece3fd 100644 --- a/doc/mf6io/prt/prt.tex +++ b/doc/mf6io/prt/prt.tex @@ -55,11 +55,11 @@ \subsubsection{Tracking} A particle which finds itself in an inactive cell will terminate with status code 7. This is consistent with MODPATH 7's behavior. -A particle in a dry but active cell, or above the water table in a partially saturated cell, need not terminate. The PRP package provides an option DRY\_TRACKING\_METHOD determining how dry particles should behave. Supported values are DROP (default), STOP, and STAY. +A particle in a dry but active cell, or above the water table in a partially saturated cell, need not terminate. We call such a particle dry. The PRP package provides an option DRY\_TRACKING\_METHOD determining how dry particles should behave. Supported values are DROP (default), STOP, and STAY. If DROP is selected, or if a DRY\_TRACKING\_METHOD is unspecified, a particle in a dry position is passed vertically and instantaneously to the water table (if the cell is partially saturated) or to the bottom of the cell (if the cell is dry). This repeats (i.e. the particle may drop through multiple cells) until it reaches the water table. Tracking then proceeds as usual. If the vertical column containing the particle is entirely dry, the particle will terminate upon reaching the bottom of the model grid. -If STOP is selected, dry particles will be terminated. +If STOP is selected, particles in dry cells, as well as particles above the water table in partially saturated cells, will be terminated. If STAY is selected, a dry particle will remain stationary until a) the water table rises and tracking can continue or b) the simulation ends.