SOLUTIONS   Ship Airwake Modeling

The expertise of CDI staff in aerodynamic modeling and computational fluid dynamics (CFD) has provided the foundation for modeling the flow field near bluff bodies such as ground structures and the superstructure of naval ships. Modeling the ship airwake is critical for the assessment of ship-rotorcraft dynamic interface (DI) issues. Advanced unsteady flow models have been developed to support DI handling qualities assessment, as well as to provide high fidelity ship airwake predictions for piloted simulation.

Ship Airwake Flow Field for Simple Frigate Shape (SFS) Model
Using CDI's In-house CFD Code and VorTran-M Software
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The CDI approach for ship airwake modeling uses a hybrid CFD method to predict the spatially- and time-varying flow field. The core computational method uses a novel combination of an efficient, robust Cartesian grid-based Euler flow solver coupled to a first-principles vorticity transport module (VorTran-M). This approach has great advantages over conventional volumetric CFD methods by minimizing the numerical diffusion present in conventional CFD methods that will result in non-physical smearing of vortices unless very high grid densities and high order methods are used. Using the CDI method, the ship airwake vorticity is transported over several ship lengths and thus avoids under-predicting the loads on the operating aircraft due to numerical dissipation. Furthermore, the combination of the Cartesian grid-based Euler solver with the VorTran-M computational methodology dramatically simplifies the mesh generation process, yielding almost turn-key application to produce high fidelity results.

Predicted Flow Tracer Trajectories for LHA with 30 Degree Wind over Deck

CDI's aerodynamic and flow field modeling approach used for ship airwake applications has been the result of several years of development and validation. A critical aspect of CDI's approach has been to develop methods that provide the correct balance between completeness in physical modeling suitable for rotorcraft flight dynamics applications with the overall computational burden. This approach is well positioned to address your simulation needs.

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