Merge branch 'fix/FC_interpolator' into 'master'

Fix/fc interpolator

Provide a fix for the interpolator in FieldUtils which currently using the wrong offset to place interpolated points back into the new field. This is mainly a problem when quad elements are listed before tri elements since this automatically leads to the incorrect offset. This would have not been a problem if tris went before quads. This MR also therefore adds in a regression test for this case.

See merge request !746

CHANGELOG.md

@@ -66,6 +66,7 @@ v4.4.0
 - Update quality metric to include scaled Jacobian output (!695)
 - Allow multiple XML files to be specified in InterpField module (!705)
 - Fix issues with isocontour module (!719)
+- Fix issue with interpolator routine (!746)
 
 **NekMesh:**
 - Modify curve module to allow for spline input (!628)

library/FieldUtils/Interpolator.cpp

@@ -339,8 +339,7 @@ void Interpolator::Interpolate(
 
         if (elmtid >= 0)
         {
-            int offset = m_expInField[0]->GetPhys_Offset(
-                m_expInField[0]->GetOffset_Elmt_Id(elmtid));
+            int offset = m_expInField[0]->GetPhys_Offset(elmtid);
 
             for (int f = 0; f < m_expInField.size(); ++f)
             {
@@ -424,8 +423,7 @@ void Interpolator::Interpolate(
 
         if (elmtid >= 0)
         {
-            int offset = m_expInField[0]->GetPhys_Offset(
-                m_expInField[0]->GetOffset_Elmt_Id(elmtid));
+            int offset = m_expInField[0]->GetPhys_Offset(elmtid);
 
             for (int f = 0; f < m_expInField.size(); ++f)
             {

utilities/FieldConvert/CMakeLists.txt

@@ -27,6 +27,7 @@ ADD_NEKTAR_TEST(cube_prismhex)
 ADD_NEKTAR_TEST(outflow_pointdatatofld)
 ADD_NEKTAR_TEST(chan3D_equispacedoutput)
 ADD_NEKTAR_TEST(chan3D_isocontour)
+ADD_NEKTAR_TEST(interpfield)
 ADD_NEKTAR_TEST(naca0012_bnd_equispacedoutput)
 ADD_NEKTAR_TEST(smallmesh_isocontour)
 

utilities/FieldConvert/Tests/interpfield.tst

+<?xml version="1.0" encoding="utf-8"?>
+<test>
+    <description> Interp field to a box of points (also calculate cp and cp0)</description>
+    <executable>FieldConvert</executable>
+    <parameters>-e -m interpfield:fromxml=interptest.xml:fromfld=interptest.fld  interptest.xml new.fld </parameters>
+    <files>
+        <file description="Session File">interptest.xml</file>
+        <file description="Session File">interptest.fld</file>
+    </files>
+    <metrics>
+        <metric type="L2" id="1">
+            <value variable="u" tolerance="1e-4">0.0254815</value>
+            <value variable="v" tolerance="1e-4">0.00331392</value>
+            <value variable="p" tolerance="1e-4">0.00229271</value>
+        </metric>
+
+<metric type="Linf" id="2">
+            <value variable="u" tolerance="1e-4">0.784991</value>
+            <value variable="v" tolerance="1e-4">0.390773</value>
+            <value variable="p" tolerance="1e-4">0.0871031</value>
+        </metric>
+    </metrics>
+</test>
+