diff --git a/src/OpenFOAM/db/IOstreams/Pstreams/PstreamGather.C b/src/OpenFOAM/db/IOstreams/Pstreams/PstreamGather.C
index 1ea68fd28b..3317663ef8 100644
--- a/src/OpenFOAM/db/IOstreams/Pstreams/PstreamGather.C
+++ b/src/OpenFOAM/db/IOstreams/Pstreams/PstreamGather.C
@@ -220,7 +220,7 @@ void Foam::Pstream::scatter(T& value, const int tag, const label comm)
     #ifndef Foam_Pstream_scatter_nobroadcast
     Pstream::broadcast(value, comm);
     #else
-    scatter(UPstream::whichCommunication(comm), value, tag, comm);
+    Pstream::scatter(UPstream::whichCommunication(comm), value, tag, comm);
     #endif
 }
 
diff --git a/src/OpenFOAM/db/IOstreams/Pstreams/PstreamReduceOps.H b/src/OpenFOAM/db/IOstreams/Pstreams/PstreamReduceOps.H
index f7942e42ad..4438e446eb 100644
--- a/src/OpenFOAM/db/IOstreams/Pstreams/PstreamReduceOps.H
+++ b/src/OpenFOAM/db/IOstreams/Pstreams/PstreamReduceOps.H
@@ -80,48 +80,13 @@ void reduce
 {
     if (UPstream::parRun())
     {
-        reduce(UPstream::whichCommunication(comm), value, bop, tag, comm);
-    }
-}
-
-
-//- Reduce (copy) and return value
-template<class T, class BinaryOp>
-T returnReduce
-(
-    const T& value,
-    const BinaryOp& bop,
-    const int tag = UPstream::msgType(),
-    const label comm = UPstream::worldComm
-)
-{
-    T work(value);
-    reduce(work, bop, tag, comm);
-    return work;
-}
-
-
-//- Reduce inplace (cf. MPI Allreduce)
-//- the sum of both value and count (for averaging)
-template<class T>
-void sumReduce
-(
-    T& value,
-    label& count,
-    const int tag = UPstream::msgType(),
-    const label comm = UPstream::worldComm
-)
-{
-    if (UPstream::parRun())
-    {
-        reduce(value, sumOp<T>(), tag, comm);
-        reduce(count, sumOp<label>(), tag, comm);
+        Foam::reduce(UPstream::whichCommunication(comm), value, bop, tag, comm);
     }
 }
 
 
 //- Reduce inplace (cf. MPI Allreduce)
-//- multiple values (identical size on all processes!)
+//- multiple values (same size on all processes!)
 template<class T, class BinaryOp>
 void reduce
 (
@@ -170,9 +135,9 @@ void reduce
 
 // * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * //
 
-// Specialisations for bool
+// Special reductions for bool
 
-//- Logical (and) reduction (cf. MPI AllReduce)
+//- Logical (and) inplace reduction. Uses UPstream::reduceAnd
 void reduce
 (
     bool& value,
@@ -181,7 +146,7 @@ void reduce
     const label comm = UPstream::worldComm
 );
 
-//- Logical (or) reduction (cf. MPI AllReduce)
+//- Logical (or) inplace reduction. Uses UPstream::reduceOr
 void reduce
 (
     bool& value,
@@ -193,7 +158,7 @@ void reduce
 
 // * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * //
 
-// Specialisations for common reduction types
+// Common reductions
 
 #undef  Pstream_CommonReductions
 #define Pstream_CommonReductions(Native)                                      \
@@ -225,7 +190,7 @@ void reduce                                                                   \
     const label comm = UPstream::worldComm                                    \
 );                                                                            \
                                                                               \
-/*! \brief Reduce (sum) multiple Native values (identical size all procs!) */ \
+/*! \brief Reduce (sum) multiple Native values (same size all procs!) */      \
 void reduce                                                                   \
 (                                                                             \
     Native values[],                                                          \
@@ -249,31 +214,14 @@ inline void reduce                                                            \
 }
 
 
-Pstream_CommonReductions(int32_t);
-Pstream_CommonReductions(int64_t);
-Pstream_CommonReductions(uint32_t);
-Pstream_CommonReductions(uint64_t);
-Pstream_CommonReductions(float);
-Pstream_CommonReductions(double);
-
-#undef Pstream_CommonReductions
-
-
 // * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * //
 
-// Specialisations for floating-point types
+// Floating-point reductions
 
 #undef  Pstream_FloatReductions
 #define Pstream_FloatReductions(Native)                                       \
                                                                               \
-/*! \brief Sum of both Native value and count (for averaging) */              \
-void sumReduce                                                                \
-(                                                                             \
-    Native& value,                                                            \
-    label& count,                                                             \
-    const int tag = UPstream::msgType(),  /*!< (ignored) */                   \
-    const label comm = UPstream::worldComm                                    \
-);                                                                            \
+Pstream_CommonReductions(Native);                                             \
                                                                               \
 /*! \brief Non-blocking reduce (sum) single Native value. Sets request */     \
 void reduce                                                                   \
@@ -297,12 +245,115 @@ void reduce                                                                   \
 );
 
 
+// * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * //
+
+Pstream_CommonReductions(int32_t);
+Pstream_CommonReductions(int64_t);
+Pstream_CommonReductions(uint32_t);
+Pstream_CommonReductions(uint64_t);
+
 Pstream_FloatReductions(float);
 Pstream_FloatReductions(double);
 
+
+// * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * //
+
+#undef Pstream_CommonReductions
 #undef Pstream_FloatReductions
 
 
+// * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * //
+
+//- Reduce inplace (cf. MPI Allreduce)
+//- the sum of both value and count (for averaging)
+template<class T>
+void sumReduce
+(
+    T& value,
+    label& count,
+    const int tag = UPstream::msgType(),
+    const label comm = UPstream::worldComm
+)
+{
+    if (UPstream::parRun())
+    {
+        Foam::reduce(value, sumOp<T>(), tag, comm);
+        Foam::reduce(count, sumOp<label>(), tag, comm);
+    }
+}
+
+
+// Floating-point sum-reduce
+
+#undef  Pstream_SumReduce
+#define Pstream_SumReduce(Native)                                             \
+                                                                              \
+/*! \brief Sum of both Native value and count (for averaging) */              \
+void sumReduce                                                                \
+(                                                                             \
+    Native& value,                                                            \
+    label& count,                                                             \
+    const int tag = UPstream::msgType(),  /*!< (ignored) */                   \
+    const label comm = UPstream::worldComm                                    \
+);
+
+
+Pstream_SumReduce(float);
+Pstream_SumReduce(double);
+
+#undef Pstream_SumReduce
+
+
+// * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * //
+
+// Convenience wrappers for some reduction operations
+// - defined after all specialisations are known
+
+//- Perform reduction on a copy, using specified binary operation
+//  \return the resulting value
+template<class T, class BinaryOp>
+T returnReduce
+(
+    const T& value,
+    const BinaryOp& bop,
+    const int tag = UPstream::msgType(),
+    const label comm = UPstream::worldComm
+)
+{
+    T work(value);
+    Foam::reduce(work, bop, tag, comm);
+    return work;
+}
+
+
+//- Perform logical (and) MPI Allreduce on a copy. Uses UPstream::reduceAnd
+//  \return the resulting value
+inline bool returnReduceAnd
+(
+    const bool value,
+    const label comm = UPstream::worldComm
+)
+{
+    bool work(value);
+    UPstream::reduceAnd(work, comm);
+    return work;
+}
+
+
+//- Perform logical (or) MPI Allreduce on a copy. Uses UPstream::reduceOr
+//  \return the resulting value
+inline bool returnReduceOr
+(
+    const bool value,
+    const label comm = UPstream::worldComm
+)
+{
+    bool work(value);
+    UPstream::reduceOr(work, comm);
+    return work;
+}
+
+
 // * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * //
 
 } // End namespace Foam
diff --git a/src/OpenFOAM/db/IOstreams/Pstreams/UPstream.H b/src/OpenFOAM/db/IOstreams/Pstreams/UPstream.H
index b884eef604..3a7438b67c 100644
--- a/src/OpenFOAM/db/IOstreams/Pstreams/UPstream.H
+++ b/src/OpenFOAM/db/IOstreams/Pstreams/UPstream.H
@@ -712,6 +712,23 @@ public:
         );
 
 
+    // Logical reductions
+
+        //- Logical (and) reduction (cf. MPI AllReduce)
+        static void reduceAnd
+        (
+            bool& value,
+            const label communicator = worldComm
+        );
+
+        //- Logical (or) reduction (cf. MPI AllReduce)
+        static void reduceOr
+        (
+            bool& value,
+            const label communicator = worldComm
+        );
+
+
     // Housekeeping
 
         //- Process index of first sub-process
diff --git a/src/Pstream/dummy/UPstreamReduce.C b/src/Pstream/dummy/UPstreamReduce.C
index cef4852701..a4f19cd7d7 100644
--- a/src/Pstream/dummy/UPstreamReduce.C
+++ b/src/Pstream/dummy/UPstreamReduce.C
@@ -30,7 +30,14 @@ License
 
 // * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * //
 
-// Specialisations for bool
+// Special reductions for bool
+
+void Foam::UPstream::reduceAnd(bool& value, const label comm)
+{}
+
+void Foam::UPstream::reduceOr(bool& value, const label comm)
+{}
+
 
 void Foam::reduce
 (
@@ -53,7 +60,7 @@ void Foam::reduce
 
 // * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * //
 
-// Specialisations for common reduction types
+// Common reductions
 
 #undef  Pstream_CommonReductions
 #define Pstream_CommonReductions(Native)                                      \
@@ -96,31 +103,14 @@ void Foam::reduce                                                             \
 {}
 
 
-Pstream_CommonReductions(int32_t);
-Pstream_CommonReductions(int64_t);
-Pstream_CommonReductions(uint32_t);
-Pstream_CommonReductions(uint64_t);
-Pstream_CommonReductions(float);
-Pstream_CommonReductions(double);
-
-#undef Pstream_CommonReductions
-
-
 // * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * //
 
-// Specialisations for floating-point types
+// Floating-point reductions
 
 #undef  Pstream_FloatReductions
 #define Pstream_FloatReductions(Native)                                       \
                                                                               \
-void Foam::sumReduce                                                          \
-(                                                                             \
-    Native& value,                                                            \
-    label& count,                                                             \
-    const int tag,                                                            \
-    const label comm                                                          \
-)                                                                             \
-{}                                                                            \
+Pstream_CommonReductions(Native);                                             \
                                                                               \
 void Foam::reduce                                                             \
 (                                                                             \
@@ -141,12 +131,32 @@ void Foam::reduce                                                             \
     const label comm,                                                         \
     label& requestID                                                          \
 )                                                                             \
+{}                                                                            \
+                                                                              \
+void Foam::sumReduce                                                          \
+(                                                                             \
+    Native& value,                                                            \
+    label& count,                                                             \
+    const int tag,                                                            \
+    const label comm                                                          \
+)                                                                             \
 {}
 
 
+// * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * //
+
+Pstream_CommonReductions(int32_t);
+Pstream_CommonReductions(int64_t);
+Pstream_CommonReductions(uint32_t);
+Pstream_CommonReductions(uint64_t);
+
 Pstream_FloatReductions(float);
 Pstream_FloatReductions(double);
 
+
+// * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * //
+
+#undef Pstream_CommonReductions
 #undef Pstream_FloatReductions
 
 
diff --git a/src/Pstream/mpi/UPstreamAllToAll.C b/src/Pstream/mpi/UPstreamAllToAll.C
index fd873d0b1f..c2551d3e59 100644
--- a/src/Pstream/mpi/UPstreamAllToAll.C
+++ b/src/Pstream/mpi/UPstreamAllToAll.C
@@ -30,7 +30,6 @@ License
 
 #include <mpi.h>
 #include <cinttypes>
-#include <cstring>  // memmove
 
 // * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * //
 
diff --git a/src/Pstream/mpi/UPstreamGatherScatter.C b/src/Pstream/mpi/UPstreamGatherScatter.C
index ee0b6f8b3c..cf14937ae9 100644
--- a/src/Pstream/mpi/UPstreamGatherScatter.C
+++ b/src/Pstream/mpi/UPstreamGatherScatter.C
@@ -30,7 +30,6 @@ License
 
 #include <mpi.h>
 #include <cinttypes>
-#include <cstring>  // memmove
 
 // * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * //
 
diff --git a/src/Pstream/mpi/UPstreamReduce.C b/src/Pstream/mpi/UPstreamReduce.C
index 970a1c59c7..b8837a89a7 100644
--- a/src/Pstream/mpi/UPstreamReduce.C
+++ b/src/Pstream/mpi/UPstreamReduce.C
@@ -34,7 +34,19 @@ License
 
 // * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * //
 
-// Specialisations for bool
+// Special reductions for bool
+
+void Foam::UPstream::reduceAnd(bool& value, const label comm)
+{
+    PstreamDetail::allReduce(&value, 1, MPI_C_BOOL, MPI_LAND, comm);
+}
+
+
+void Foam::UPstream::reduceOr(bool& value, const label comm)
+{
+    PstreamDetail::allReduce(&value, 1, MPI_C_BOOL, MPI_LOR, comm);
+}
+
 
 void Foam::reduce
 (
@@ -44,8 +56,6 @@ void Foam::reduce
     const label comm
 )
 {
-    // This can also work:
-    // PstreamDetail::allReduce(&value, 1, MPI_BYTE, MPI_BAND, comm);
     PstreamDetail::allReduce(&value, 1, MPI_C_BOOL, MPI_LAND, comm);
 }
 
@@ -58,15 +68,13 @@ void Foam::reduce
     const label comm
 )
 {
-    // This can also work:
-    // PstreamDetail::allReduce(&value, 1, MPI_BYTE, MPI_BOR, comm);
     PstreamDetail::allReduce(&value, 1, MPI_C_BOOL, MPI_LOR, comm);
 }
 
 
 // * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * //
 
-// Specialisations for common reduction types
+// Common reductions
 
 #undef  Pstream_CommonReductions
 #define Pstream_CommonReductions(Native, TaggedType)                          \
@@ -126,49 +134,17 @@ void Foam::reduce                                                             \
     (                                                                         \
         values, size, TaggedType, MPI_SUM, comm                               \
     );                                                                        \
-}                                                                             \
-
-
-Pstream_CommonReductions(int32_t, MPI_INT32_T);
-Pstream_CommonReductions(int64_t, MPI_INT64_T);
-Pstream_CommonReductions(uint32_t, MPI_UINT32_T);
-Pstream_CommonReductions(uint64_t, MPI_UINT64_T);
-Pstream_CommonReductions(float,   MPI_FLOAT);
-Pstream_CommonReductions(double,  MPI_DOUBLE);
-
-#undef Pstream_CommonReductions
+}
 
 
 // * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * //
 
-// Specialisations for floating-point types
+// Floating-point reductions
 
 #undef  Pstream_FloatReductions
 #define Pstream_FloatReductions(Native, TaggedType)                           \
                                                                               \
-void Foam::sumReduce                                                          \
-(                                                                             \
-    Native& value,                                                            \
-    label& count,                                                             \
-    const int tag,  /* (unused) */                                            \
-    const label comm                                                          \
-)                                                                             \
-{                                                                             \
-    if (UPstream::parRun())                                                   \
-    {                                                                         \
-        Native values[2];                                                     \
-        values[0] = value;                                                    \
-        values[1] = static_cast<Native>(count);                               \
-                                                                              \
-        PstreamDetail::allReduce<Native>                                      \
-        (                                                                     \
-            values, 2, TaggedType, MPI_SUM, comm                              \
-        );                                                                    \
-                                                                              \
-        value = values[0];                                                    \
-        count = static_cast<label>(values[1]);                                \
-    }                                                                         \
-}                                                                             \
+Pstream_CommonReductions(Native, TaggedType);                                 \
                                                                               \
 void Foam::reduce                                                             \
 (                                                                             \
@@ -199,12 +175,47 @@ void Foam::reduce                                                             \
     (                                                                         \
         values, size, TaggedType, MPI_SUM, comm, &requestID                   \
     );                                                                        \
+}                                                                             \
+                                                                              \
+void Foam::sumReduce                                                          \
+(                                                                             \
+    Native& value,                                                            \
+    label& count,                                                             \
+    const int tag,  /* (unused) */                                            \
+    const label comm                                                          \
+)                                                                             \
+{                                                                             \
+    if (UPstream::parRun() && UPstream::nProcs(comm) > 1)                     \
+    {                                                                         \
+        Native values[2];                                                     \
+        values[0] = static_cast<Native>(count);                               \
+        values[1] = value;                                                    \
+                                                                              \
+        PstreamDetail::allReduce<Native>                                      \
+        (                                                                     \
+            values, 2, TaggedType, MPI_SUM, comm                              \
+        );                                                                    \
+                                                                              \
+        count = static_cast<label>(values[0]);                                \
+        value = values[1];                                                    \
+    }                                                                         \
 }
 
 
+// * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * //
+
+Pstream_CommonReductions(int32_t, MPI_INT32_T);
+Pstream_CommonReductions(int64_t, MPI_INT64_T);
+Pstream_CommonReductions(uint32_t, MPI_UINT32_T);
+Pstream_CommonReductions(uint64_t, MPI_UINT64_T);
+
 Pstream_FloatReductions(float, MPI_FLOAT);
 Pstream_FloatReductions(double, MPI_DOUBLE);
 
+
+// * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * //
+
+#undef Pstream_CommonReductions
 #undef Pstream_FloatReductions