Wednesday, October 7, 2015

How to compute the forces on a sail

The following video shows how Stallion 3D computes the forces on a sail.  The forces are computed from an .stl file of the flying sail shape and the deck of the sailboat.  Grid generation is automatic and Stallion 3D solves the Reynolds Averaged Navier-Stokes (RANS) to accurately compute the forces and moments acting on the geometry.

More information can be obtained from http:/

Thanks for reading.

Saturday, September 26, 2015

Passenger Car Aerodynamics

When we think of computing the external aerodynamics on a passenger car, we often assume a super-computer and months of grid generation are necessary for the task. However, Stallion 3D with HIST (Hanley Innovations Surface Treatment) can accomplish the task on your ordinary Windows Laptop or PC running 7, 8 or 10.

DrivAer model solution using Stallion 3D - RANS solver.

No Simplifications

Stallion 3D makes no simplification in the physics of the problem. Instead, it utilizes the computation power that is hidden in your personal computer (64 bit & multi-cores technologies). The software simultaneously solves seven unsteady nonlinear partial differential equations on your PC. Five of these equations (the Reynolds Averaged Navier-Stokes, RANS) ensure conservation of mass, momentum and energy for a compressible fluid. Two additional equations captures the dynamics of a turbulent flow field.

Actual Geometry Analysis

Stallion 3D does not require a grid from the user because grid generation is automatic. Also, it is not necessary to defeature the geometry. This saves weeks or even months in the solution of automobile aerodynamics problems.  The unique CFD technique employed by Stallion 3D gives users a tremendous advantage over other methods because they can analyze more cases in a shorter period of time.

The Results

The following video shows how Stallion 3D solves a difficult problem. In the problem, the software accurately computes the drag on a passenger car. Accurate computations of drag is necessary for sizing engines, fuel systems and designing fuel efficient vehicles.

More information can be found at or telephone us at (352) 240-3658.

Thanks for reading.

Tuesday, August 18, 2015

OpenVSP Workshop 2015

NASA OpenVSP (Open Vehicle Sketch Pad) is an innovative tool for creating a functioning aircraft from scratch.  The software is an excellent tool for the conceptual and preliminary design of UAVs, light aircraft or transonic jet. More about OpenVSP can be found at http/  OpenVSP is free and runs on most personal computers.

Cessna 210 - Created in OpenVSP & Analyzed in Stallion 3D (2 Million cells)

I had the opportunity to make a presentation at OpenVSP Workshop 2015.   My presentation was an overview of using Stallion 3D to perform the aerodynamics of designs created in OpenVSP.  Stallion 3D reads in a design in the .stl format and then computes the aerodynamics performance.  Stallion 3D does not require user grid generation.  A user can go from design to results of their actual geometry in 2 - 6 hours using Stallion 3D.

The following slides are from my presentation:

More information about Stallion 3D can be found at:

If you are using OpenVSP in your company to develop unique aircraft designs, please contact me at (352) 240-3658.  We can provide you with more information about using Stallion 3D for your particular design.

Thanks for reading.

Tuesday, May 19, 2015

Hot Supersonic Jet

Do you ever wonder how hot a supersonic jet would become if it flew at sea-level at 3.5 the speed of sound (Mach 3.5)?  Well, put your thoughts to rest.  Here is the answer:

Step 1.  Grab a CAD file from the Sketchup 3D warehouse.  A great one is the SR-71 model.

Step 2.  Convert it to .stl format and read it into Stallion 3D.

Step 3.  Have Stallion 3D solve the Navier-Stokes equations at Mach 3.5 (1,200 meters/second).

Step 4.  Walk away for 3 hours (if you are using a 2 GHz laptop and 500 k cells) and return to find the "answer".

The surface pressure in Pascals:

 Pressure on the surface of the jet as rendered in Stallion 3D with HIST.

The Hanley Discretization (HD) technologies accurately solves
the complete flow field and displays surface Cp (near the fuselage) within a 
few hours using Windows XP, 7 or 8/8.1

The Mach Number:

Stallion 3D applies a no-slip velocity condition to
the surface for this particular problem.  The 
program can also solve the compressible Euler equations.

The temperature:

Yes. It gets hot on the surface of a supersonic jet flying at sea-level as speed more than the speed of sound. The temperature can become as hot as 770 degrees Celsius on the surface.

Surface temperature in degrees Kelvin

Temperature on wing section near the fuselage of the jet.

Stallion 3D with Hanley Innovations Surface Treatment (HIST) along with Hanley Discretization  (HD) solves difficult problem once only tractable with countless days of grid generation and super-computing time.  And guess what?  It solves them in just a few hours on ordinary laptops and tablets computers.

More information about Stallion 3D can be found at  Please call me at (352) 240-3658 to further the discussion.

Thanks for reading.

Sunday, February 1, 2015

Stallion 3D Ahmed Body Validation

Stallion 3D with HIST (Hanley Innovations Surface Treatment) features automatic grid generation and high accuracy for arbitrary  3D geometries.  Stallion 3D features solutions of both the 3D compressible Euler and Navier-Stokes equations.   

Stallion 3D: Flow past Ahmed Body

The compressible Euler solver (for low speed flows) was used to analyze the Ahmed body geometry for validation of solutions for road vehicles and race cars (F1 for example).  Stallion 3D has the ability to read in a complex geometry and provide a quick solution on an ordinary PC or laptop computer under Windows XP, 7 or 8/8.1.  

Stallion 3D Workflow and Results

With 700,000 computational cells, the Euler solver computed a pressure drag of 0.254 after 15,000 iterations.  This is very close to the experimental results of 0.260.

More information about Stallion 3D can be found at  

Thanks for reading.

Friday, November 14, 2014

Rosetta Orbiter in Wake of Comet 67P

AG/CFD (Actual Geometry) Analysis performed by Stallion 3D with HIST for #SimulationFriday.

Stallion 3D took just seconds (with no need for pre-processing) to automatically import, grid and begin the compressible Navier-Stokes analysis of the water vapor, ice particles and dust streaming past the Rosetta orbiter in the wake of Comet 67-P’s.

Close up of the orbiter geometry in Stallion 3D.  

Analysis for the arbitrary geometries was performed on a on an HP Pavillion Laptop (Quad-Core) for a total of 4 hours.
Streamline of the flow past the Rosetta Orbiter

Rosetta image Credit:

More information can be found at

Thanks for reading.

Thursday, September 25, 2014

Stallion 3D Lift/Drag Study

Stallion 3D is a modern  aerodynamics and computational fluid dynamics (CFD) analysis software tool.  The software allows users to bypass the time-consuming grid generation step and setup their problem for analysis in just a matter of a few seconds.  Stallion 3D is the best tool for aerodynamics analysis of arbitrary geometries on your MS Windows PC.

The following pictures are results obtain using Stallion 3D for  a lift and drag study of the DLR F4 wing-body.    The geometry was obtained from NASA OpenVsp hangar. Extensive data for this study was obtained from NASA 1st Drag Prediction Workshop (DPW1).  The url is:

Only 500,000 computation cells were used for the present Stallion 3D analysis.  Results were obtained after 4 hours of computation time for each angle of attack using a laptop computer under MS Windows.  To speed-up the simulations, two cases were run simultaneously on the laptop.  This allowed a complete study in less than 24 hours.

Stallion 3D pressure distribution for DLR F4 at 2 deg angle of attack

CL versus angle of attack.  Results are from Stallion 3D
and CFL3D (as reported during DPW1).

Lift vs. Drag for the DLR F4 wing body.  Since the 
Euler equations was used for Stallion 3D, the graph shows 
pressure drag (CD_pres) for Stallion 3D.  This is compared
against the total drag from CFL3D and the experiments.

Pressure coefficient a station along the wing at 2 deg angle of attack.
The lines are for results obtained  by CFD3D as presented at DPW1.

More information about Stallion 3D can be obtained from

Thanks for reading.  Do not hesitate to telephone us at (352) 240-3658 or email at if you have any questions.