An Overview of Computational Fluid Dynamics Dr. Nor Azwadi bin Che Sidik Faculty of Mechanical Engineering Universiti Teknologi Malaysia INSPIRING CREATIVE AND INNOVATIVE MINDS 1
What is CFD? C computational <--> Experimental F Fluid <--> Solid D Dynamics <--> Static CFD is the analysis of systems involving fluid flow, heat transfer and associated phenomena such as chemical reactions by means of computer based simulation INSPIRING CREATIVE AND INNOVATIVE MINDS
Analysis techniques (EFD) (AFD) (CFD) INSPIRING CREATIVE AND INNOVATIVE MINDS
Comparison of techniques INSPIRING CREATIVE AND INNOVATIVE MINDS
CFD Modeling CFD modeling can be divided into two types: i) Numerical modeling computer solution on mathematical physics problem. ii) Commercial CFD software modeling computer solution on engineering problem. INSPIRING CREATIVE AND INNOVATIVE MINDS
Numerical Modeling Fluid Mechanics Physics of Fluid Mathematics Navier-Stokes Equations Numerical Methods Discretized Form Fluid Problem C F D Geometry Simulation Results Computer Computer Program Grids Comparison& Analysis Programming Language
Physics of Fluids Viscous vs. inviscid External flow or internal flow Turbulent vs. laminar Incompressible vs. compressible Single- vs. multi-phase Thermal/density effects Free-surface flow and surface tension Chemical reactions and combustion etc INSPIRING CREATIVE AND INNOVATIVE MINDS
INSPIRING CREATIVE AND INNOVATIVE MINDS Navier-Stokes equation ˆ z u y u x u x p z u w y u v x u u t u ˆ z v y v x v y p z v w y v v x v u t v 0 z w y v x u t p RT Convection Pressure gradient Viscous terms Continuity equation Equation of state ˆ z w y w x w z p z w w y w v x w u t w Local acceleration
Discretisation method Discretization Methods Finite Difference Straightforward to apply, simple, sturctured grids Finite Element Any geometries Finite Volume Conservation, any geometries INSPIRING CREATIVE AND INNOVATIVE MINDS
Grid Structured Grid + all nodes have the same number of elements around it only for simple domains Unstructured Grid + for all geometries irregular data structure
Computer program Ex:Matlab, Fortran, C++, etc INSPIRING CREATIVE AND INNOVATIVE MINDS
Simulation results INSPIRING CREATIVE AND INNOVATIVE MINDS
Commercial CFD Software Some of the famous softwares: Ansys Fluent StarCD Flowtherm Solidworks
Three main elements: How does Commercial CFD works? 1.Pre Processor.Solver 3.Post Processor
Pre-Processor Consists of the input of a flow problem to CFD User Activities: define geometry & generate grid (50% time) selection of phenomena to be modeled definition of fluid properties specification of boundary and initial conditions
Pre-Processor Consists of the input of a flow problem to CFD User Activities: define geometry & and computational domain
Pre-Processor Consists of the input of a flow problem to CFD User Activities: specification of boundary and initial conditions
Pre-Processor Consists of the input of a flow problem to CFD User Activities: generate grid
Pre-Processor Consists of the input of a flow problem to CFD User Activities: definition of fluid properties turbulent and incompressible flow Types of turbulent modelling Large eddy simulation model
Solver Three primary numerical solution techniques finite difference, finite element, finite control volume The numerical method performs the following: Approximates the unknown variables by simple functions Discretization by substitution of the approx-imations into the governing flow equations and subsequent mathematical manipulations Solution of the algebraic equations
Post processor Provides a user friendly way to look at the results of a simulation Domain geometry and grid display Vector Plots Contour Plots Particle Tracking
CFD Results
Where is CFD used? Aerospace Automotive Biomedical Chemical Processing HVAC Hydraulics Marine Oil & Gas Power Generation Sports Aerospace Automotive F18 Store Separation Biomedical Temperature and natural convection currents in the eye following laser heating. 3
Where is CFD used? Aerospacee Automotive Biomedical Chemical Processing HVAC Hydraulics Marine Oil & Gas Power Generation Sports Chemical Processing Polymerization reactor vessel - prediction of flow separation and residence time effects. Hydraulics HVAC Streamlines for workstation ventilation 4
Marine (movie) Sports Where is CFD used? Aerospace Automotive Biomedical Chemical Processing HVAC Hydraulics Marine Oil & Gas Power Generation Sports Oil & Gas Flow of lubricating mud over drill bit Power Generation Flow around cooling towers 5
Thank you 6