Changeset 4825

Timestamp:

Nov 17, 2007, 5:58:06 AM (17 years ago)

Author:

ole

Message:

Really simple and attractive way of controlling vertex momenta. This came to me in the early hours Saturday morning and has yet to be tested properly.

File:

• anuga_core/source/anuga/shallow_water/shallow_water_ext.c (modified) (3 diffs)

anuga_core/source/anuga/shallow_water/shallow_water_ext.c

@@ -558 +558 @@
   double hv[3], h; // Depths at vertices
   double Fx, Fy; // Froude numbers
+  double uc, vc; // Centroid speeds
 
   // Compute linear combination between w-limited stages and
@@ -702 +703 @@
         }
 
-        // Update momentum as a linear combination of
-        // xmomc and ymomc (shallow) and momentum
-        // from extrapolator xmomv and ymomv (deep).
-        // FIXME (Ole): Is this really needed?
-        xmomv[k3+i] = (1-alpha)*xmomc[k] + alpha*xmomv[k3+i];
-        ymomv[k3+i] = (1-alpha)*ymomc[k] + alpha*ymomv[k3+i];
+        // Update momentum at vertices
+        if (tight_slope_limiters == 1) {        
+          // FIXME(Ole): Here's what I think (as of 17 Nov 2007) 
+          // we need to do. Simple and efficient:
+        
+          // Speeds at centroids
+          if (hc_k > epsilon) {
+            uc = xmomc[k]/hc_k;
+            vc = ymomc[k]/hc_k;
+          } else {
+            uc = 0.0;
+            vc = 0.0;
+          }
+          // Vertex momenta guaranteed to be consistent with depth guaranteeing
+          // controlled speed
+          xmomv[k3+i] = uc*hv[i];
+          ymomv[k3+i] = vc*hv[i];       
+        } else {
+          // Update momentum as a linear combination of
+          // xmomc and ymomc (shallow) and momentum
+          // from extrapolator xmomv and ymomv (deep).
+          // FIXME (Ole): Is this really needed?
+          
+          xmomv[k3+i] = (1-alpha)*xmomc[k] + alpha*xmomv[k3+i];
+          ymomv[k3+i] = (1-alpha)*ymomc[k] + alpha*ymomv[k3+i];
+        
+        }
       }
     }
@@ -722 +744 @@
       
       // FIXME (Ole): currently only used with tights_SL
+      
+      // FIXME (Ole): may not be necessary now
 
       excessive_froude_number=0;