Non-Inertial Reference Frame Motion

Adapting non-inertial reference frame model results to enable visualization from a stationary frame of reference is a nifty new feature coming in the upcoming releases of FlowSight™ for FLOW-3D CAST v4.2 (next month) and FLOW-3D v11.2 (late 2016). This brief note describes this feature and gives a couple examples.

Many real-world processes happen in accelerating or non-inertial reference frames. Examples of such processes include sloshing of fuel in satellite tanks and centrifugal casting. FLOW-3D has long incorporated in its solver the ability to model fluid and solid motion using a non-inertial reference frame model (NIRF), but lacked the ability to visualize the motion depicted from a stationary frame of reference. After the introduction of the General Moving Objects (GMO) model, users could have their cake and eat it, too: modeling the coupled fluid-solid motion and visualizing the resulting motion in a realistic way. Unfortunately, the GMO model comes with a price in terms of computational time. While the NIRF may be more computationally convenient for solving large problems, the inability to analyze the solution from a stationary frame of reference frustrated many users. FlowSight’s recent development makes it easy to apply the NIRF feature to all parts of a case, such as iso-surfaces, clips and streamlines, allowing the user to view the rigid body motion and the fluid flow from a stationary reference frame.

NIRF motion can be captured in animations that are created by FlowSight. The user can activate only one or both of the possible motions – rotation and translation. The scale of the translational motion can be adjusted for better visualization in cases where the translations are huge, like aerospace applications where the moving body can translate for miles.

Below are two animations with NIRF motions that model tilt pour and centrifugal casting.

Tilt pour casting with NIRF motion on the left and stationary motion on the right

Centrifugal casting with NIRF motion on the top and stationary motion on the bottom left

In the upcoming few blogs, I will discuss the featured developments of FLOW-3D CAST v4.2.