About grid generation in constructions bounded by the surfaces of revolution

For constructions bounded by the surfaces of revolution, structured grid generation technique is presented. Its technology has been elaborated within the variational approach for constructing optimal grids satisfying optimality criteria: closeness of grids to uniform ones, closeness of grids to orthogonal ones and adaptation to a given function. Grid generation has been designed for numerical solution of the differential equations modeling the vortex processes of multi-component hydrodynamics. In the technology, the three-dimensional construction in which it is required to construct a grid is represented in the form of the curvilinear hexahedron defining its configuration. The specific feature of the required configurations is that some faces of a curvilinear hexahedron lie in one plane and along edges of adjoining faces grid cells degenerate into prisms. Grid generation in the considered constructions has started to be developed by the elaboration of algorithms for the volume of revolution which has become the basic construction. The basic construction is obtained by the rotation through 180? around the axis of a generatrix consisting of straight line segments, arcs of circles and ellipses. Then the deformed volumes of revolutions are considered along with the generalizations of the volume of revolution which represent constructions obtained by the surfaces of revolution with parallel axis of rotation. The aim of the further development of the technology is to consider more and more complicated constructions and elaborate the technology for them. In the presentation, the current state of the development of the technology is given. Examples of generated grids are supplied.

Effectiveness of multiple jets for a finned large slenderness ratio missile in supersonic crossflows

The reaction control system with multiple lateral jets shows great advantages in agility and maneuverability for supersonic air vehicles. Interactions among sonic jet plumes, X-shape fins, and supersonic crossflow at Mach 4.5 and Reynolds number 3.8 × 107 are numerically studied considering different number of jets for a large slenderness ratio missile with 7 jet exits. Three-dimensional Reynolds-averaged Navier–Stokes equations closed by Spalart–Allmaras turbulence model for the structured grid are validated and solved. The overall force and moment amplification factors of configurations with and without fins are analyzed and compared. Moreover, the force and moment amplification factors on fins and ratio of force and moment on fins are proposed and discussed to measure the jet effectiveness contributed from fins. The number of jet plumes is under consideration for all cases. Results show that the increment of effectiveness decreases as the number of jets increases for the finned configuration. Fins can significantly improve the jet effectiveness with more than 70% force and 50% moment increment, which shows great advantages to the jet effectiveness as well as the overall aerodynamic performance.

VERIFICATION OF THE DIFFUSION AND TRANSPORT SOLVERS WITHIN DIF3D FOR 3D HEXAGONAL GEOMETRIES

The DIF3D code (DIFfusion 3D) has been a workhorse of fast reactor analysis work at Argonne National Laboratory for over 40 years. DIF3D was primarily built in the late 1970s as a three-dimensional multigroup diffusion equation solver operating on semi-structured grid geometries. In the mid-1990s, transport capabilities needed for high-leakage reactor configurations were added to DIF3D with the variational anisotropic nodal transport approach. Recent reactor design activities at Argonne are requiring that a thorough verification of the Argonne Reactor Computation (ARC) codes be performed. With DIF3D being central to the entire ARC system, the verification efforts are focused on the 3D Cartesian, 3D triangular, and 3D hexagonal core geometry options of DIF3D. Validation activities, while needed for the ongoing design activities at Argonne, are handled at a project-specific level. This paper summarizes the verification work so far on the forward and adjoint forms of the fixed source, inhomogeneous fixed source, and k-eigenvalue steady state transport and diffusion equations as implemented specifically for 3D triangular and hexagonal geometries in DIF3D. Since analytic solutions of the neutron diffusion and transport equations are either limited in scope or not possible, this verification required multiple tiers of problems unique to each solver and geometry type, each testing features independent and complementary arguments for why this separate testing of functionalities is acceptable. This separate testing was also supplemented with a high-level integral check of each the diffusion and transport capabilities and applicable geometries.

User-intervened structured meshing methods and applications for complex flow fields based on multiblock partitioning

Recently, a series of automatic structured grid generation methods for different fields or specific problems have been proposed by various researchers, but these methods still have some disadvantages or limitations. Therefore, in the present study, several user-intervened structured meshing methods for complex flow fields have been introduced for multiblock docking and multiblock splicing based on multiblock structured grid technology. Besides, three applications compared with the other methods or experiments are discussed to illustrate the crucial workflow of the user-intervened partitioning. The successful implementation of these partitioning examples demonstrates the feasibility and effectiveness of the methods described herein. And the techniques and criteria summarized in the present paper are quite practical and helpful for high-quality meshing.

Theory and verification of a new 3D RANS wake model

This paper details the background to the WakeBlaster model: a purpose-built, parabolic three-dimensional RANS solver, developed by ProPlanEn. WakeBlaster is a field model, rather than a single turbine model; it therefore eliminates the need for an empirical wake superposition model. It belongs to a class of very fast (a few core seconds, per flow case) mid-fidelity models, which are designed for industrial application in wind farm design, operation, and control. The domain is a three-dimensional structured grid, a node spacing of a tenth of a rotor diameter, by default. WakeBlaster uses eddy viscosity turbulence closure, which is parameterized by the local shear, time-lagged turbulence development, and stability corrections for ambient shear and turbulence decay. The model prescribes a profile at the end of the near wake, and the spatial variation of ambient flow, by using output from an external flow model.