1. Node-Cell Values and Mesh Adaption
CFD for Thermal Analysis
Larry Yu BSc, MSc, PhD, CEng, MIET, MASME
Principal Simulation Engineer
26/07/2016
C. Soteriou PhD, CMath, CSci, FIMA
Manager, Simulation & Physical Modelling

2. CFD for thermal analysis
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• Objectives:
 Investigate specific problems in 2D and 3D analysis of heat in orifice
 Develop a more efficient way (best practice) for injector nozzle analysis
with thermal considerations
• Approach:
 Same 2D settings and meshing scheme for 3D analysis
 Temperature specific issues in post-processing
 Node values and cell values
 Effective mesh adaption
Inlet
Orifice
outlet
Axis
Wall

3. Mesh adaption and temperature values
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Temperature in cell values (K)Cell mesh adaption
• Original problems in heat modelling:
 Unrealistically low temperature results at the wall around the orifice entry
 Very fine mesh is required to start the analysis – longer time to run
• Problems solved by:
 Using mesh adaption, and
 Comparing node values with cell values
Temperature in node values (K)
Cells are refined

4. CFD results – Temperature along the wall
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Temperature(K)
Nodevalues
Temperature(K)
Cellvalues
Before mesh adaption After mesh adaption

5. CFD for Heat in Orifice Conclusions
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• Cell values are the data for Fluent finite volume method
 Used in problem solving and saved in the data file
• Node values are calculated from cell values
 Used for post-processing, not involved in the computation of problem
solution and may give unrealistic min and max values for temperature
• Mesh adaption can refine cell sizes next to the wall
 Can move the min node values close to cell values, but thin wall cells
increase the max temperature (need further investigation)
 Increases 2D cell number by 2 folds and 3D by 3 folds each adaption
• 3D Cd is 0.932, compared to 2D Cd of 0.934
 Therefore 2D models are suitable to the analysis of heat in orifice