An Introduction to Recent CFD Technique from CAD to Solver (CATIA-ICEM CFD-CFX 5.7)

BeomSeok KIM 

Department of Mechanical Engineering, Graduate school of Korea Maritime University

The 2004 KIT-KNCT-KMU Lab. Joint SeminarKorea Maritime University, BUSAN30 July – 01 August, 2004

Procedure of General CFD AnalysisProcedure of General CFD Analysis

3D Modeling

Meshing

Solving

Design

Post-processing

CATIA, Solidworks, Pro-Engineer

Convergence problem?Coarse? – Quality check!!

Rough surface?

Modification?

3D Modeling CATIA, Solidworks, Pro-Engineer etc.

Meshing ICEM-CFD 5.0, Grid Pro, Hyper Mesh etc.

Solving CFX-5.7, CFX-TASCflow, Fluent, Star-CD etc.

Post-processing AVS, Ensight, Field View, Amira etc.

Procedure of General CFD AnalysisProcedure of General CFD Analysis

3D-Modeling for Flow Meter: CATIA V5 R13

Inlet Filter

Casing

Pivot Shaft

Bearing

Shaft Guide

Rotor

Guide Vain

Casing Cover

ICEM-CFDICEM-CFD

• ICEM: Integrated Computational Engineering and Manufacturing

- CFD VersionPre and Post Processor without Load, Constraint and Properties tabs. Includes Prism meshing. Write mesh for 100+ CFD solvers.

- FSICombination of FEA and CFD features

• Modernized and Integrated GUI• Wide CAD support• Mid-Plane Extractions/Extensions• Geometry Creation/Repair/Simplification

Ref. : The 2004 International ANSYS Conference, Pittsburg, USA

• Powerful Meshing tools

• Tetra from CAD, CAD and mesh, or mesh

• Shell meshing, patch dependent, patch independent, mapped, structured/unstructured

• Hex-dominant, unstructured hexa, structured hexa, extruded quads

• Advanced mesh editing

• Hexa Meshing Structured/Unstructured

• Boundary Conditions

• Output to 100+ Solvers

• Post processing

• Scriptable … and much more…

I-DEASI-DEAS

SolidWorksSolidWorks

Pro/EngineerPro/Engineer

UnigraphicsUnigraphics

Solid EdgeSolid Edge

CATIACATIA

• 3rd Party Cad• IGES• ACIS• Parasolid• DWG/DXF• GEMS

• Faceted Data• STL• VRML• NASTRAN, P

ATRAN, ANSYS, LS-DYNA

Wide CAD Support

Tetra Meshing

• Automatic Surface and Volume Meshing• Patch Independent• Surface mesh not required to generate volume mesh

• Surface mesh can be saved independently• Very tolerant of imperfect geometry

Tetra Meshing

• Most commercial Tet mesh generators• First generate a Tri surface mesh

• surface-by-surface• Every edge of every surface must be resolved

• sensitive to • sliver surfaces, • bad surface parameterization• surface connectivity (gaps)

• If the surface mesh is complete• volume mesh is generated from surface mesh Mesh detail

Tetra Meshing

• ICEM Tetra uses patch-independent, Octree method• Volume mesh

• generated independent of surface model• Mesh is projected to model surfaces, curves and

points• Surface mesh is created

• Resulting mesh is independent of the underlying arrangement of surfaces

Sliver ignored

Hexa Meshing

• High-powered hexahedral grid generation• Top-down or Bottom-up blocking approach• Allows rapid creation of complex topologies• Fast Iteration Cycle

• Elastic blocking can be fit to schematically similar geometry

• Replay Files for parametric geometry changes

• Prism layer • improve boundary layer resolution for

tetrahedral mesh• Hex and Tet zones joined by a pyramid layer

Hybrid Meshing

Mesh Generation – Flow Meter

• Inletpipe : 140,000 nodes• Outpipe : 100,000 nodes• Using Hybrid Mesh : Tetra - Prism• Complex Domain : Created by separately

Inletpipe

Outpipe

Prism Layer

Mesh Generation – Flow Meter

• Rotating Part : 510,000 nodes• Using Hybrid Mesh : Tetra - Prism• Complex Domain : Created by separately

Mesh Generation – Flow Meter

CFX-5.7CFX-5.7

• Advanced coupled multigrid linear solver technology • Unmatched meshing flexibility • Superb parallel efficiency • Excellent pre and post-processing capabilities • A wide range of physical models that interoperate with each other providing real answers to industrial problems

- Multiphase Flows - Bubbly Flows- Free Surface Flows- Particle Tracking- Mass Transfer : Cavitation, Boiling, Condensation, Evaporation

Ref. :http://www.cfxkorea.com

Boundary Conditions – Flow MeterInlet : 0.4444kg/sec.

Outlet : Pressure (Averaged at Whole Surface)

GGI Grid Surface matching : Frozen Rotor

GGI Grid Surface matching : Frozen Rotor

Rotating : 800 rpm

Grid Interface

=

=

• Non overlap regions are created if interface sides do not fit perfectly (this should be avoided where possible)• Completely overlapping integration point faces• Partly non-overlapping integration point faces• Complete non-overlapping integration point faces

• Slip walls are used at non-overlapping regions

Ref. :CFX-5.7 Basic Training Course, CFX-Korea

Compressor and Scroll

Combined Tet and Hex mesh

Interface Model : Frozen Rotor

Computation Results : Flow Meter

• 720,000 node

• Hybrid Mesh• Steady State/Frozen Rotor• RNG-KE/Water at 25• Rotating Speed: 800RPM• Mass Flow-rate: 0.444kg/s

• • Velocity vector at mid-sectionVelocity vector at mid-section

• • 3-D Clipping View 3-D Clipping View

• • Velocity vector at inlet pipe Velocity vector at inlet pipe • • Velocity vector at out pipe Velocity vector at out pipe

Computation Results : Flow Meter

• Calculated Torque at Rotating Blade : 0.0017592N M

• • StreamlinesStreamlines • • Surface pressureSurface pressure

Computation Results : Butterfly Valve• • Computational MeshComputational Mesh

• 98,000 nodes• Hybrid Mesh : Tetra-Prism• RNG-KE/Steady State• Approaching Velocity : 3m/s• Water at 25

InletInlet

OutletOutlet

SymmetrySymmetry

Computation Results : Butterfly Valve

• Pipe Length : 2m• Diameter : 0.4m• Axis Symmetric Flow Field• Open Angle : 45 deg.

• • Isometric ViewIsometric View

• • Surface PressureSurface Pressure

Computation Results : Butterfly Valve• • Stream Lines behind Valve PlateStream Lines behind Valve Plate • • Stream Lines from Inlet to OutletStream Lines from Inlet to Outlet

• • Velocity VectorVelocity Vector • • Surface PressureSurface Pressure

• Calculated Torque at V/V Plate : 30.4568 N M