write out sources even when no exact solution is present. Run one patch injection example

LDDsimulation/LDDsimulation.py

@@ -315,8 +315,8 @@ class LDDsimulation(object):
         self._init_exact_solution_expression()
         self._init_DirichletBC_dictionary()
         self._init_simulation_output()
-        if self.exact_solution and self.write2file['solutions']:
-            df.info(colored("writing exact solution for all time steps to xdmf files ...", "yellow"))
+        if self.write2file['solutions']:
+            df.info(colored("writing exact solutions and/or source terms for all time steps to xdmf files ...", "yellow"))
             self.write_exact_solution_to_xdmf()
         self._initialised = True
 
@@ -903,27 +903,31 @@ class LDDsimulation(object):
         for subdom_ind, subdomain in self.subdomain.items():
             file = self.solution_file[subdom_ind]
             for timestep in self.timesteps_to_plot:
+                source = dict()
+                if self.exact_solution:
                     exact_pressure = dict()
                     S = self.saturation[subdom_ind]
                     saturation_w = df.Function(subdomain.function_space["pressure"]['wetting'])
                     saturation_nw = df.Function(subdomain.function_space["pressure"]['wetting'])
-                source = dict()
+
                 for phase in subdomain.has_phases:
                     f_expr = subdomain.source[phase]
-                    pa_exact = subdomain.pressure_exact[phase]
-                    pa_exact.t = timestep
                     f_expr.t = timestep
-                    exact_pressure.update(
-                        {phase: df.project(pa_exact, subdomain.function_space["pressure"][phase])}
-                        )
                     source.update(
                         {phase: df.project(f_expr, subdomain.function_space["pressure"][phase])}
                     )
-                    exact_pressure[phase].rename("exact_pressure_"+"{}".format(phase), "exact_pressure_"+"{}".format(phase))
-                    file.write(exact_pressure[phase], timestep)
                     source[phase].rename("source_"+"{}".format(phase), "source_"+"{}".format(phase))
                     file.write(source[phase], timestep)
 
+                    if self.exact_solution:
+                        pa_exact = subdomain.pressure_exact[phase]
+                        pa_exact.t = timestep
+                        exact_pressure.update(
+                            {phase: df.project(pa_exact, subdomain.function_space["pressure"][phase])}
+                            )
+                        exact_pressure[phase].rename("exact_pressure_"+"{}".format(phase), "exact_pressure_"+"{}".format(phase))
+                        file.write(exact_pressure[phase], timestep)
+                if self.exact_solution:
                     exact_capillary_pressure = df.Function(subdomain.function_space["pressure"]['wetting'])
                     if subdomain.isRichards:
                         exact_capillary_pressure.assign(-exact_pressure['wetting'])