Tuesday October 10, 2017 at 11:28am
Applications Engineer Chris Boyles explores the accuracy of SOLIDWORKS Simulation.
Previously we have had a look at the accuracy of SOLIDWORKSSimulation and now we are going to have a look at Flow Simulation. Unlike
Simulation, Flow Simulation doesn’t have any bodies or organisations which run
benchmarking tests that have been run against it. Instead, to “Benchmark” Flow
Sim SOLIDWORKS have validated the software against test and empirical data for
over 20 flow problems. You can have a look at the whole validation document for
Flow Simulation in your install directory:
Directory: \Program Files\SOLIDWORKS Corp\SOLIDWORKS Flow Simulation\lang\
We will have a look at a few of them in this blog.
Fluid flow around a circular cylinder is one of the most
researched problems in fluid dynamics and SOLIDWORKS Flow Simulation is able to
simulate it very accurately. Flow around a cylinder is actually very
complicated and its behaviour is very dependent on the Reynold’s number of the
Flow; which takes into account the density of the fluid, velocity of the fluid,
characteristic length of the body (diameter in this case) and the dynamic
viscosity of the fluid. As long as the Reynold’s number of the flow passing
over the cylinder is the same as another case, the result should be directly
The example used in the validation looks at low Reynolds
number flows, which produces two steady vortices formed symmetrically behind
the cylinder. The image below shows the flow trajectories of result of the FlowSimulation above and an image of such flow below for comparison.
As you can see SOLIDWORKS Flow Simulation is able to
correctly predict the vortex shedding at low Reynolds numbers. However, what
about high Reynolds numbers?
Well if we take a look at the results, we get very close to
the empirical data. First we will have a look at the Strouhal number (which is
a dimensionless number describing the oscillatory flow mechanisms) of the flow
against the Reynolds number.
The blue line is the empirical data and the red triangles are
SOLIDWORKS Flow Simulation results. As you can see it is staying accurate to
the data spread. We also see a similar trend with the coefficient of drag
against Reynold’s number plot.
Again, we see that the results from the SOLIDWORKS FlowSimulation follows the trend of the empirical data accurately, giving you
confidence in the results that you can achieve with this package.
If we take a look at another example, Plate Fin Heat Sink
Cooling by Forced Convection. The study tested an aluminium heatsink which is
heated by a 10 W electrical heater placed on top of a polystyrene block in a
wind tunnel and tested at 5 different flow conditions.
The performance of the heat sink is
estimated by a thermal resistance defined as:
Where q is the total
power input of the heat source (10W).
The 5 different flow
cases tested are as follows:
Now if we compare the results of
the Flow Simulation study to the experimental data we can see a clear trend in
the data where Flow Simulation is correctly able to simulate the forced
convection of the heat sink.
In the blog I’ve tried to keep the
technicality to a minimum, however if you are interested in the math
calculations of the theory shown here, want to have a look at the flow
simulation set up files or take a look at all of the other Flow Simulation
validation examples have a look at the validation document. The files used
along with their set up are located in:
Directory: \Program Files\SOLIDWORKS Corp\SOLIDWORKS Flow Simulation\Validation
If you’re interested in the
accuracy of SOLIDWORKS Simulation as well, have a look at the blog found here:
'So how accurate is SOLIDWORKS Simulation?'