From 8a2f65940cbef1ba10c18dc272a527ea96c5725f Mon Sep 17 00:00:00 2001
From: andy <a.heather@opencfd.co.uk>
Date: Fri, 5 Jun 2009 16:39:21 +0100
Subject: [PATCH] changed (old) linearised Cu coeff to momentum transfer
 coefficient

---
 .../submodels/Kinematic/DragModel/DragModel/DragModel.C    | 5 ++---
 .../submodels/Kinematic/DragModel/DragModel/DragModel.H    | 7 +++----
 2 files changed, 5 insertions(+), 7 deletions(-)

diff --git a/src/lagrangian/intermediate/submodels/Kinematic/DragModel/DragModel/DragModel.C b/src/lagrangian/intermediate/submodels/Kinematic/DragModel/DragModel/DragModel.C
index f1b98e609c..1eb7f86b48 100644
--- a/src/lagrangian/intermediate/submodels/Kinematic/DragModel/DragModel/DragModel.C
+++ b/src/lagrangian/intermediate/submodels/Kinematic/DragModel/DragModel/DragModel.C
@@ -64,12 +64,11 @@ const Foam::dictionary& Foam::DragModel<CloudType>::dict() const
 
 
 template<class CloudType>
-Foam::scalar Foam::DragModel<CloudType>::Cu
+Foam::scalar Foam::DragModel<CloudType>::ptc
 (
     const vector& Ur,
     const scalar d,
     const scalar rhoc,
-    const scalar rhop,
     const scalar mu
 ) const
 {
@@ -79,7 +78,7 @@ Foam::scalar Foam::DragModel<CloudType>::Cu
 
     const scalar Cd = this->Cd(Re);
 
-    return 3.0*Cd*rhoc*magUr/(4.0*d*rhop);
+    return Cd*rhoc*magUr/8.0;
 }
 
 
diff --git a/src/lagrangian/intermediate/submodels/Kinematic/DragModel/DragModel/DragModel.H b/src/lagrangian/intermediate/submodels/Kinematic/DragModel/DragModel/DragModel.H
index 9fae0e9b11..69130b168c 100644
--- a/src/lagrangian/intermediate/submodels/Kinematic/DragModel/DragModel/DragModel.H
+++ b/src/lagrangian/intermediate/submodels/Kinematic/DragModel/DragModel/DragModel.H
@@ -120,14 +120,13 @@ public:
         //- Return drag coefficient
         virtual scalar Cd(const scalar Re) const = 0;
 
-        //- Return linearised coefficient for velocity equation
-        //  Drag force per unit particle mass = Cu(U - Up)
-        scalar Cu
+        //- Return momentum transfer coefficient
+        //  Drag force per unit particle surface area = ptc(U - Up)
+        scalar ptc
         (
             const vector& Ur,
             const scalar d,
             const scalar rhoc,
-            const scalar rhop,
             const scalar mu
         ) const;
 };