fix: prohibit int_comp > 0 with model_eqns = 3 (THINC leaves int_en stale)

Author: sbryngelson

src/simulation/m_checker.fpp

@@ -35,6 +35,7 @@ contains
         end if
 
         call s_check_inputs_time_stepping
+        call s_check_inputs_interface_compression
 
         @:PROHIBIT(ib_state_wrt .and. .not. ib, "ib_state_wrt requires ib to be enabled")
 
@@ -106,4 +107,13 @@ contains
 
     end subroutine s_check_inputs_nvidia_uvm
 
+    !> Checks constraints on interface compression parameters
+    impure subroutine s_check_inputs_interface_compression
+
+        @:PROHIBIT(int_comp /= 0 .and. model_eqns == 3, &
+                   & "int_comp > 0 is not supported with model_eqns = 3: THINC does not update " &
+                   & // "per-fluid internal energies, leaving thermodynamically inconsistent face states")
+
+    end subroutine s_check_inputs_interface_compression
+
 end module m_checker

toolchain/mfc/case_validator.py

@@ -388,9 +388,14 @@ def check_interface_compression(self):
         int_comp = self.get("int_comp", 0)
         n = self.get("n", 0)
         num_fluids = self.get("num_fluids", 0)
+        model_eqns = self.get("model_eqns", 2)
         self.prohibit(int_comp not in [0, 1, 2], "int_comp must be 0 (off), 1 (THINC), or 2 (MTHINC)")
         self.prohibit(int_comp == 2 and n == 0, "int_comp = 2 (MTHINC) requires at least 2D (n > 0)")
         self.prohibit(int_comp != 0 and num_fluids != 2, "int_comp > 0 requires num_fluids = 2")
+        self.prohibit(
+            int_comp != 0 and model_eqns == 3,
+            "int_comp > 0 is not supported with model_eqns = 3: THINC does not update per-fluid internal energies, leaving thermodynamically inconsistent face states",
+        )
 
         recon_type = self.get("recon_type", 1)
         if recon_type == 1:  # WENO