Dr. Len Imas Awarded ONR Grant to Investigate Applicability of Probabalistic Computational Fluid Dynamic Methods to Problems Involving Cavitation




September 23, 2013

Dr. Len Imas of the Department of Civil, Environmental and Ocean Engineering at Stevens Institute of Technology has been awarded a grant from the Office of Naval Research (ONR) to develop and validate a numerical algorithm for a probabilistic description of fluid flow with an initial application to investigate flows around partially-cavitating hydrofoils.

“The understanding of cavitation phenomena in external flows enables the engineering of high speed vessels, particularly in the context of performance and control,” says Dr. Michael Bruno, Dean of the Charles V. Schaefer, Jr. School of Engineering and Science. “This type of numerical hydrodynamics research is a vital component in efforts to establish the next generation of marine vessels for the Navy.”

According to Dr. Alan Blumberg, Director of the Davidson Laboratory, “Len’s innovative work in computational marine hydrodynamics is crucial to providing understanding that will enable engineers to work with more realistic analysis tools.”

The objective of this effort is to develop and evaluate a numerical uncertainty quantification tool for Navier-Stokes based simulations using an algorithm based on non-intrusive polynomial chaos, with an initial application to modeling of flows around partially-cavitating hydrofoils. Uncertainty quantification becomes a necessity due to the fact that the underlying analysis and simulation tools employed in marine hydrodynamics are typically applied with a unique set of input data and model variables, whereas realistic operating conditions are a superposition of numerous uncertainties under which the marine system of interest operates. For example, when performing a 3-D viscous flow analysis, there is uncertainty in the definition of the boundary conditions representing the operational environment; in the discrepancy between the CAD geometry and the real geometry resulting from the manufacturing tolerances and assembly process; in the true deformed geometry of the components being analyzed, etc. In addition, modeling uncertainties exist due to, but are not limited to, turbulence treatment, multiphase model formulation, numerical discretization schemes, grid dependency, etc. This leads to a global uncertainty on the results of the analysis, on which design decisions ultimately have to be made. The ability to quantify the impact of these uncertainties on the predicted hydromechanics of the marine vehicle and to account for those uncertainties in the design process is crucial for reliable performance analysis and risk management.

Len Imas, Associate Professor of Ocean Engineering, holds a BS and MEng. in Aeronautical Engineering from Rensselaer Polytechnic Institute, and a PhD. in Numerical Hydrodynamics from Massachusetts Institute of Technology . His interests are in basic and applied research involving hydrodynamics and computational fluid mechanics related to topics ranging from nonlinear free-surface turbulent flows, to vortex induced vibrations, to high-speed surface and sub-surface marine vehicles, and to high-performance racing yachts. His specialization is in the development and utilization of computational fluid mechanics and optimization methods in design analysis applications involving marine hydrodynamics and low speed aerodynamics.

The Davidson Laboratory was founded in 1935 and remains one of the world’s leading facilities for naval architecture research. The laboratory's renowned towing tank complex is 320 feet long, 16 feet wide and 8 feet deep. With recently upgraded instrumentation, glass walls for viewing and photography, and public access improvements, the facility is vital to the Laboratory's contributions to fundamental and applied research in ship design, hydrodynamics and ocean engineering.

About the Davidson Laboratory

The Davidson Laboratory at Stevens Institute of Technology works to preserve and secure U.S. maritime resources and assets through collaborative knowledge development, innovation and invention, and education and training. Composed of four integrated laboratory activities and three support groups, it has become the world’s leader in delivering new knowledge, advanced technology, and education in support of the maritime community. It uniquely integrates the fields of naval architecture, coastal and ocean engineering, physical oceanography, marine hydrodynamics and maritime security to create a trans-disciplinary enterprise that can address both the highly-specialized issues confronting each discipline, as well as the more complex, integrated issues facing natural and man-made maritime systems.

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