Initialise the radiative loss counter to 0 on start-up.

src/const.h

@@ -95,8 +95,8 @@
 //#define EXTERNAL_POTENTIAL_DISK_PATCH
 
 /* Cooling properties */
-//#define COOLING_NONE
-#define COOLING_CONST_DU
+#define COOLING_NONE
+//#define COOLING_CONST_DU
 //#define COOLING_CONST_LAMBDA
 //#define COOLING_GRACKLE
 

src/cooling/const_du/cooling.h

@@ -53,6 +53,7 @@
  * @param us The internal system of units.
  * @param cooling The #cooling_function_data used in the run.
  * @param p Pointer to the particle data.
+ * @param xp Pointer to the extended particle data.
  * @param dt The time-step of this particle.
  */
 __attribute__((always_inline)) INLINE static void cooling_cool_part(
@@ -103,7 +104,27 @@ __attribute__((always_inline)) INLINE static float cooling_timestep(
 }
 
 /**
- * @brief Initialises the cooling properties.
+ * @brief Sets the cooling properties of the (x-)particles to a valid start
+ * state.
+ *
+ * In this case, we set the total radiated energy to 0. Note that the particle
+ * structure is just passed in for cases where information needs to be read
+ * from there.
+ *
+ * @param p Pointer to the particle data.
+ * @param xp Pointer to the extended particle data.
+ */
+__attribute__((always_inline)) INLINE static void cooling_init_part(
+    const struct part* restrict p, struct xpart* restrict xp) {
+
+  xp->cooling_data.radiated_energy = 0.f;
+}
+
+/**
+ * @brief Initialises the cooling function properties from the parameter file
+ *
+ * In this example, we just read in the values from the YAML file without
+ * doing any conversions or multiplying any constants in.
  *
  * @param parameter_file The parsed parameter file.
  * @param us The current internal system of units.

src/cooling/const_du/cooling_struct.h

@@ -51,6 +51,11 @@ struct cooling_function_data {
  * This is used to carry properties such as the total amount of
  * energy radiated away.
  */
-struct cooling_xpart_data {};
+struct cooling_xpart_data {
+
+  /*! Amount of energy radiated away by this particle since the start of the run
+   */
+  float radiated_energy;
+};
 
 #endif /* SWIFT_COOLING_STRUCT_CONST_DU_H */

src/cooling/const_lambda/cooling.h

@@ -138,6 +138,19 @@ __attribute__((always_inline)) INLINE static float cooling_timestep(
   return u / du_dt;
 }
 
+/**
+ * @brief Sets the cooling properties of the (x-)particles to a valid start
+ * state.
+ *
+ * @param p Pointer to the particle data.
+ * @param xp Pointer to the extended particle data.
+ */
+__attribute__((always_inline)) INLINE static void cooling_init_part(
+    const struct part* restrict p, struct xpart* restrict xp) {
+
+  xp->cooling_data.radiated_energy = 0.f;
+}
+
 /**
  * @brief Initialises the cooling properties.
  *

src/cooling/const_lambda/cooling_struct.h

@@ -48,9 +48,14 @@ struct cooling_function_data {
   float cooling_tstep_mult;
 };
 
+
 /**
- * @brief Properties of the cooling stored in the particle data
+ * @brief Properties of the cooling stored in the particle data.
  */
-struct cooling_xpart_data {};
+struct cooling_xpart_data {
+
+  /*! Amount of energy radiated away by this particle since the start of the run */
+  float radiated_energy;
+};
 
 #endif /* SWIFT_COOLING_STRUCT_CONST_LAMBDA_H */

src/cooling/none/cooling.h

@@ -71,6 +71,18 @@ __attribute__((always_inline)) INLINE static float cooling_timestep(
   return FLT_MAX;
 }
 
+/**
+ * @brief Sets the cooling properties of the (x-)particles to a valid start
+ * state.
+ *
+ * Nothing to do here.
+ *
+ * @param p Pointer to the particle data.
+ * @param xp Pointer to the extended particle data.
+ */
+__attribute__((always_inline)) INLINE static void cooling_init_part(
+    const struct part* restrict p, struct xpart* restrict xp) {}
+
 /**
  * @brief Initialises the cooling properties.
  *

src/space.c

@@ -42,6 +42,7 @@
 /* Local headers. */
 #include "atomic.h"
 #include "const.h"
+#include "cooling.h"
 #include "engine.h"
 #include "error.h"
 #include "gravity.h"
@@ -1471,6 +1472,23 @@ void space_init_parts(struct space *s) {
   }
 }
 
+/**
+ * @brief Initialises all the extra particle data
+ *
+ * Calls cooling_init_xpart() on all the particles
+ */
+void space_init_xparts(struct space *s) {
+
+  const size_t nr_parts = s->nr_parts;
+  struct part *restrict p = s->parts;
+  struct xpart *restrict xp = s->xparts;
+
+  for (size_t i = 0; i < nr_parts; ++i) {
+
+    cooling_init_part(&p[i], &xp[i]);
+  }
+}
+
 /**
  * @brief Initialises all the g-particles by setting them into a valid state
  *
@@ -1630,6 +1648,7 @@ void space_init(struct space *s, const struct swift_params *params,
 
   /* Set the particles in a state where they are ready for a run */
   space_init_parts(s);
+  space_init_xparts(s);
   space_init_gparts(s);
 
   /* Init the space lock. */