cleaning up documentation of new rel perm for frozen B&C

src/pks/flow/constitutive_relations/wrm/rel_perm_frzBC_evaluator.cc

@@ -4,10 +4,11 @@
   The terms of use and "as is" disclaimer for this license are
   provided in the top-level COPYRIGHT file.
 
-  Authors: Ethan Coon (ecoon@lanl.gov), Bo Gao (gaob@ornl.gov)
+  Authors: Ethan Coon (ecoon@lanl.gov)
+           Bo Gao (gaob@ornl.gov)
 */
 
-//! RelPermFrzBCEvaluator: evaluates relative permeability using water retention models.
+//! Evaluates relative permeability using an empirical model for frozen conditions.
 #include "rel_perm_frzBC_evaluator.hh"
 
 namespace Amanzi {
@@ -101,8 +102,8 @@ RelPermFrzBCEvaluator::InitializeFromPlist_()
   // cutoff above 0?
   min_val_ = plist_.get<double>("minimum rel perm cutoff", 0.);
   perm_scale_ = plist_.get<double>("permeability rescaling");
-  omega_ = plist_.get<double>("scale dependent parameter", 2.0);
-  b_ = plist_.get<double>("Clapp and Hornberger b", 2.0);
+  omega_ = plist_.get<double>("omega [-]", 2.0);
+  b_ = plist_.get<double>("Clapp and Hornberger b [-]", 2.0);
 }
 
 

src/pks/flow/constitutive_relations/wrm/rel_perm_frzBC_evaluator.hh

@@ -4,10 +4,11 @@
   The terms of use and "as is" disclaimer for this license are
   provided in the top-level COPYRIGHT file.
 
-  Authors: Ethan Coon (ecoon@lanl.gov), Bo Gao (gaob@ornl.gov)
+  Authors: Ethan Coon (ecoon@lanl.gov)
+           Bo Gao (gaob@ornl.gov)
 */
 
-//! Evaluates relative permeability using water retention models.
+//! Evaluates relative permeability using an empirical model for frozen conditions.
 /*!
 
 This is an empirical relative permeability model according to Niu and Yang (2006). 
@@ -17,15 +18,13 @@ used for freezing conditions to make snowmelt water infiltrate deeper. See paper
 Agnihotri et al. (2023) for discussions about the influence of relative permeability 
 model on discharge under freezing conditions.
 
-Uses a list of regions and water retention models on those regions to evaluate
-relative permeability, typically as a function of liquid saturation and gas saturation.
+.. math::
+   k_{rel} = .... \omega
 
-Most of the parameters are provided to the WRM model, and not the evaluator.
-Typically these share lists to ensure the same water retention curves, and this
-one is updated with the parameters of the WRM evaluator.  This is handled by
-flow PKs. 
-
-Some additional parameters are available.
+Note this implementation is currently a bit inconsistent in that it uses WRMs
+to get the residual saturation, and uses a global value for b, the Clapp and
+Hornberger parameter (equivalent to 1/lambda in Brooks & Corey).  This will be
+fixed shortly (see ticket #196) to make b spatially variable by WRM.
 
 .. _rel-perm-evaluator-spec
 .. admonition:: rel-perm-evaluator-spec
@@ -49,10 +48,10 @@ Some additional parameters are available.
      and K_sat is very small.  To avoid roundoff propagation issues, rescaling
      this quantity by offsetting and equal values is encourage.  Typically 10^7 or so is good.
 
-   * `"omega`" ``[double]`` A scale dependent parameter in the relative permeability model. 
-     See paper Niu & Yang (2006) for details about the model. Set it to 2-3 should be good.
+   * `"omega [-]`" ``[double]`` **2.0** A scale dependent parameter in the relative permeability model. 
+     See paper Niu & Yang (2006) for details about the model. Typical values range from 2-3.
 
-   * `"b`" ``[double]`` Clapp-Hornberger b parameter.
+   * `"Clapp and Hornberger b [-]`" ``[double]`` **2.0** Clapp-Hornberger b parameter.
 
    * `"WRM parameters`" ``[wrm-typedinline-spec-list]``  List (by region) of WRM specs.
 
@@ -67,8 +66,7 @@ Some additional parameters are available.
 
 */
 
-#ifndef AMANZI_FLOWRELATIONS_REL_PERM_FrzBC_EVALUATOR_
-#define AMANZI_FLOWRELATIONS_REL_PERM_FrzBC_EVALUATOR_
+#pragma once
 
 #include "wrm.hh"
 #include "wrm_partition.hh"
@@ -127,4 +125,3 @@ class RelPermFrzBCEvaluator : public EvaluatorSecondaryMonotypeCV {
 } // namespace Flow
 } // namespace Amanzi
 
-#endif