This section gives a brief description of a general workflow of a typical CFD process.
It describes in short the problem description, pre-processing, solving and post-processing
aspects of a CFD workflow.
The entire workflow of a typical CFD analysis can be summarized as follows. Figure 1. Basic Workflow
AcuSolve is a robust software that does all of the above steps
of CFD and provides the accurate solution to the problem.
General Workflow
The accurate simulation of a flow field using CFD requires a number of steps to be taken.
In order to set the problem up properly for simulation it is necessary to first understand
the physics. Once the physics have been understood a model can be constructed. The following
steps describe the set of steps that should be taken when performing a CFD simulation.
Problem Description
Though often neglected, this step is the foremost important aspect of a successful
CFD simulation. Before attempting a CFD simulation a clear description of the problem
is necessary. This step involves the following tasks.
Identify the domain of interest: Though in principle domain of any size can be
analysed with CFD simulation, it is often wise to choose the critical regions in
which flow field is of importance and simulate the flow in that domain. Minimizing
the size of the domain keeps the simulation costs low, but comes at the expense of
introducing non physical behavior in the simulation by having boundaries too close
to regions in the flow where the results are of interest. It is important to
select boundaries where the flow character is known so that proper boundary
conditions can be applied.
Identify the nature of the flow: It is always helpful to make an educated guess
on the nature of the flow, such as whether it is steady/transient,
laminar/turbulent, thermal/non thermal. For example, while analysing a flow in a
pipe that has low Reynolds number, say Re ~ 100, it is useful to perform a laminar
analysis rather than doing an expensive turbulent flow analysis with a larger mesh
count. In case of turbulent flows, it is advisable to choose turbulence model
based on the physics present, while keeping in mind the areas where the flow will
be critical.
Pre-Processing
This process involves geometry import, mesh generation and specifying the relevant
physics equations to be solved. Pre-processing also involves defining the fluid
properties, boundary conditions and body force parameters. AcuSolve uses HyperWorks CFD and SimLab for the pre-processing of the geometry and the mesh
generation.
Solving
Solving is the critical part of a CFD simulation. The governing flow equations are
discretized. All these algebraic equations are then solved for the unknown flow
parameters. The final solution is the quantitative representation of these parameters
at the mesh generated nodes. As a first step of solving, the AcuPrep module of AcuSolve checks for
the compatibility of the information provided in the pre-processing step. The source
of errors in AcuPrep could be because of insufficient
inputs, syntax errors, and so on. After AcuPrep the actual
solving of equations is performed.
Post-Processing
Having solved for the unknowns, the next step is the analysis of this huge data to
obtain relevant insight. This data can be analysed either in the form of contour plots
or tabular data to identify the critical portions of the flow field.
