Big Data, Big Challenge

Capturing helicopter interactions with a ship's airwake in flight simulation made possible with in situ XDB workflow.

An image from work described in “Coupled Flight Simulator and CFD Calculations of Ship Airwake using HPCMP CREATE™–AV Kestrel”, James R. Forsythe et al, AIAA 2015-0556. Disclaimer: The US Government and Dept. of the Navy do not endorse products or services.

The CREATE™–AV team undertook a simulation challenge last year: coupling the CFD solver HPCMP CREATE–AV Kestrel to the Navy flight simulator CASTLE® for a fully coupled rotorcraft simulation in a ship’s airwake. While high-fidelity ship airwake simulation data has been used with helicopter landing simulations, it had been based on queries of a static database.  This project marks the first time that the flight simulation system has incorporated helicopter and ship airwake interactions into the simulation.  Capturing the important interactions results in much higher realism and training quality.

Intelligent Light provided software and expertise to solve extraordinary challenges presented by the size of the data, the need to move it quickly, and to process and visulize the results.  Intractable with traditional CFD workflows, Intelligent Light's unique In-situ XDB workflow solved the problem.

The approach, hover and landing sequence had a simulation duration of 45 seconds. The time to save, transfer and read these visualization files along with the massive space required to save them emerged as a significant roadblock to success.

In-situ XDB Workflow via VisIt/libsim provided the solution. The CREATE–AV team, aided by Intelligent Light, integrated VisIt’s in-situ post-processing library libsim into Kestrel. The resulting workflow created and saved FieldView XDBs (extract databases) as the simulation ran on the HPC resource. FieldView was then used for all visual flight checks and movie generation, without the burden of dealing with the volume grid and results.

"The long time-scales and high frequency content due to the blade motion made visualization a challenge, so an ability to create feature extracts was created using VisIt libsim's capability to extract FieldView13 xdb files. This enabled the creation of animations at a physical resolution of 60Hz (every five iterations) over the 45 seconds simulated. The resulting 2700 extracts were post-processed using FieldView in batch and in parallel to render the animations in a few hours rather than the days it would have otherwise taken. This capability should be in a future release of Kestrel."

- J. Forsythe, C. Lynch, S. Polsky, and P. Spalart, "Coupled Flight Simulator and CFD Calculations of Ship Airwake using HPCMP CREATE™-AV Kestrel", AIAA paper 2015-0556

See AIAA 2015-0556 for details and acknowledgements.

Related webinar: CREATE™–AV team and Intelligent Light tackle 45 seconds of flight time with unique in situ XDB workflow