CFD/FEA Guides
A CFD Engineer is one who uses CFD software (for example ANSYS CFX, ANSYS Fluent) suitable to solve internal or external flow field of the desired geometry by solving complex numerical simulations. The solution is analysed at the end to simulate CFD analysis which assists in the design optimisation process or predicting performance at an early stage of design phase.CFD simulation is performed at several stages depending on the application, accuracy and computational power as well as time available. Beginning from the Euler solutions that are yielded by several approximations, to the complex Large Eddy Simulation (LES-Turbulence modelling) with some approximations and the most realistic Direct Numerical Simulation (DNS) with no approximations (no turbulence modelling) and Navier Stokes (NS) equation in original form to capture all eddy scales which are given below:
Euler or potential Flow
2D planar /axisymmetric Navier Stokes Solution
3D Navier Stokes Solution
Reynolds Averaged Navier Stokes(RANS) Solution
Unsteady Reynolds Averaged Navier Stokes (URANS)
Large Eddy Simulation(LES)
Direct Numerical Simulations(DNS)
A CFD Engineer arrives at a CFD result by following a step by step procedure listed below:
Creating Geometry of the object or Extracting Fluid domain
mesh generation or Grid generation
Choosing a flow model or physics (for example Turbulence, Combustion and Multiphase..)
Applying Boundary and Initial Conditions.
Solving Flow Field.
Results or Post processing.
Geometry modelling, it begins with constructing a 2D or 3D geometry in a commercially available CAD software. Sometimes a CAD software is embedded in many CFD software’s in the grid generator component for example Design Modeller in ANSYS software. Though, discrete CAD tools are also widely used, and the geometry is exchange into the CFD package by the CFD engineer. The imported geometry is performed an geometry clean-up operation before meshing that involves checking the integrity of surface constraints, alignment of mating surfaces, removing of short edges by merging or connecting with neighbouring face or edge and filling up gaps if any. These edges fall in the list of interfaces which creates the flow direction for the solver and similarly allows the passage of flow variables within the interfaces during simulation.