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SUMMARYIn a recent paper Gresho and Sani' showed that Dirichlet and Neumann boundary conditions for the pressure Poisson equation give the same solution. The purpose of this paper is to confirm this (for one case at least) by numerically solving the pressure equation with Dirichlet and Neumann boundary conditions for the inviscid stagnation point flow problem. The Dirichlet boundary condition is obtained by integrating the tangential component of the momentum equation along the boundary. The Neumann boundary condition is obtained by applying the normal component of the momentum equation at the boundary. In this work solutions for the Neumann problem exist only if a compatibility condition is satisfied. A consistent finite difference procedure which satisfies this condition on non-staggered grids is used for the solution of the pressure equation with Neumann conditions. Two test cases are computed. In the first case the velocity field is given from the analytical solution and the pressure is recovered from the solution of the associated Poisson equation. The computed results are identical for both Dirichlet and Neumann boundary conditions. However, the Dirichlet problem converges faster than the Neumann case. In the second test case the velocity field is computed from the momentum equations, which are solved iteratively with the pressure Poisson equation. In this case the Neumann problem converges faster than the Dirichlet problem.

<span style="font-size: 10pt; font-family: ";Times New Roman";,";serif";; mso-fareast-font-family: 'Times New Roman'; mso-ansi-language: EN-US; mso-fareast-language: EN-US; mso-bidi-language: AR-SA;">Thermal effects impact the flow around and within structures.<span style="mso-spacerun: yes;">  </span>This computational study assesses features that affect the heating and buoyancy, and thus, the resulting flow both internal and external to a building.<span style="mso-spacerun: yes;">  </span>Considerations include the importance of time of day, building materials, sky cover, etc. on the local thermal heating of a passive solar building.<span style="mso-spacerun: yes;">  </span>Such impacts are assessed using full thermal coupling between a building energy simulation model and a computational fluid dynamics model, including the effects of thermal radiation, conduction, and convection to analyze the impact of all natural heating, cooling, and flow mechanisms for both the interior and exterior.<span style="mso-spacerun: yes;">    </span>Unique features such as Trombe walls add to heat transfer mechanisms.<span style="mso-spacerun: yes;">  </span>Analysis is made for three separate seasonal conditions.</span>

A computational-fluid-dynamics-based modeling effort to capture flow through an axial flow waterjet propulsor is presented. The effort covered the waterjet flow over a wide range of flow coefficients and into cavitation-driven breakdown. The computations are presented in cavitation at two values of flow coefficient through a series of decreasing operating inlet total pressure. The computational results are compared to experimental measurements. Suction-surface and tip-gap cavitation patterns are presented and compared to experimental photographs. Presented computational solutions are blade-passage steady and periodic. The computational results apply a powering iteration methodology to facilitate coupling of rotor, stator, and inflow and outflow ducting.