Publication Detail

Fast 3D Flow Simulations of a Waterjet Propulsion System

Xian Luo, Chryssostomos Chryssostomidis, George Em Karniadakis
9 pp.

In this paper we present a new method to simulate 3D flow in complex-geometry moving domains and we apply it to study the flow patterns in a waterjet-like system. In particular, we combine the spectral element method [5] with the smoothed profile method (SPM, [11], [12] and [14]), an approach similar in spirit to the popular immersive boundary method but more suitable for high-order methods. SPM uses a fixed nonconforming mesh and represents the moving domains by smooth profiles, which are used to construct a penalty force term in the Navier-Stokes equations. Its similarity with the immersed boundary method is that they both use a force distribution to effectively impose the constraints associated with the flow boundary conditions. However, for spectral element discretizations, the smooth profile of SPM leads to high-order accuracy as it does not cause Gibbs phenomena at the geometric interfaces.

We analyze the accuracy of the new hybrid method for a prototype flow problem and show that the modeling error (due to smooth profiles) is a non-monotonic function of the time step size and the interface thickness of the smooth profile. This new method is applied to simulate 3D complexgeometry moving domains such as propellers in free-space and impellers in ducts, which are key components of the waterjet propulsion system. We present flow results for various rotational speeds, Reynolds numbers, and pressure gradients in order to elucidate the mechanisms of thrust generation in waterjet systems. In terms of computational efficiency of the method, the new approach is more than 100 times faster than using the often-employed arbitrary Lagrangian Eulerian (ALE) for simulations in moving domains and can be run on single processor computers.

type: Technical reports

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Parent Project

Project No.: 2008-ESRDC-01-LEV
Title: Electric Ship Research and Development Consortium (ESRDC)

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