From 19b3b2e563d0e9c64e18c0ed96cd656196216a1e Mon Sep 17 00:00:00 2001
From: Will Bainbridge <http://cfd.direct>
Date: Wed, 23 Mar 2022 13:00:58 +0000
Subject: [PATCH] tutorials: reverseBurner: Ignite with temperature constraint

This method of igniting is easier to control than a heat-source based
method. A suitable temperature at which the reaction will take is
typically fairly easy to estimate, whilst determining a heat source
value which achieves the same effect is difficult and is often requires
trial and error.

The new fractional control of value constraints has permitted the use of
fixedTemperatureConstraint in this way; both because it allows for
ramping and for limiting the duration over which the constraint is
applied.
---
 .../reverseBurner/constant/gas/fvModels       | 17 ---------
 .../reverseBurner/system/gas/fvConstraints    | 35 +++++++++++++++++++
 2 files changed, 35 insertions(+), 17 deletions(-)
 create mode 100644 tutorials/heatTransfer/chtMultiRegionFoam/reverseBurner/system/gas/fvConstraints

diff --git a/tutorials/heatTransfer/chtMultiRegionFoam/reverseBurner/constant/gas/fvModels b/tutorials/heatTransfer/chtMultiRegionFoam/reverseBurner/constant/gas/fvModels
index 6888b483cd..770c1d1159 100644
--- a/tutorials/heatTransfer/chtMultiRegionFoam/reverseBurner/constant/gas/fvModels
+++ b/tutorials/heatTransfer/chtMultiRegionFoam/reverseBurner/constant/gas/fvModels
@@ -14,23 +14,6 @@ FoamFile
 }
 // * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * //
 
-ignition
-{
-    type            heatSource;
-
-    selectionMode   cellSet;
-    cellSet         ignition;
-
-    q
-    {
-        type        scale;
-        scale       squarePulse;
-        start       0;
-        duration    1;
-        value       5e7;
-    }
-}
-
 radiation
 {
     type    radiation;
diff --git a/tutorials/heatTransfer/chtMultiRegionFoam/reverseBurner/system/gas/fvConstraints b/tutorials/heatTransfer/chtMultiRegionFoam/reverseBurner/system/gas/fvConstraints
new file mode 100644
index 0000000000..f4231c1dfc
--- /dev/null
+++ b/tutorials/heatTransfer/chtMultiRegionFoam/reverseBurner/system/gas/fvConstraints
@@ -0,0 +1,35 @@
+/*--------------------------------*- C++ -*----------------------------------*\
+  =========                 |
+  \\      /  F ield         | OpenFOAM: The Open Source CFD Toolbox
+   \\    /   O peration     | Website:  https://openfoam.org
+    \\  /    A nd           | Version:  dev
+     \\/     M anipulation  |
+\*---------------------------------------------------------------------------*/
+FoamFile
+{
+    format      ascii;
+    class       dictionary;
+    location    "constant";
+    object      fvConstraints;
+}
+// * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * //
+
+ignition
+{
+    type            fixedTemperatureConstraint;
+
+    selectionMode   cellSet;
+    cellSet         ignition;
+
+    mode            uniform;
+
+    temperature     2000;
+
+    fraction
+    {
+        type            table;
+        values          ((0 0) (0.1 0) (0.2 1) (0.4 1) (0.5 0));
+    }
+}
+
+// ************************************************************************* //