[Algorit] Simplify normal stress computation

src/one-body-sample.cc

@@ -188,24 +188,9 @@ int main(int argc, char *argv[]) {
     };
     Vector ell(fineVertexCount);
     computeExternalForces(0.0, ell);
-
-    double normalStress;
-    {
-      double volume = 1.0;
-      for (size_t i = 0; i < dims; ++i)
-        volume *= (myGeometry.C[i] - myGeometry.A[i]);
-
-      double area = 1.0;
-      for (size_t i = 0; i < dims; ++i)
-        if (i != 1)
-          area *= (myGeometry.C[i] - myGeometry.A[i]);
-
-      // volume * gravity * density / area    = normal stress
-      // V      * g       * rho     / A       = sigma_n
-      // m^d    * N/kg    * kg/m^d  / m^(d-1) = N/m^(d-1)
-      normalStress = -volume * parset.get<double>("gravity") *
-                     parset.get<double>("body.density") / area;
-    }
+    double normalStress = (myGeometry.A[1] - myGeometry.C[1]) *
+                          parset.get<double>("gravity") *
+                          parset.get<double>("body.density");
     FrictionData const frictionData(parset.sub("boundary.friction"),
                                     normalStress);