A fully automated Chimera methodology for multiple moving body problems

Chen

Engineering Applications of Computational Fluid Mechanics

et al. 2016

Three issues are tackled in this study to improve the robustness of local remeshing techniques. Firstly, the local remeshing region (hereafter referred to as 'hole') is initialized by removing low-quality elements and then continuously expanded until a certain element quality is reached after remeshing. The effect of the number of the expansion cycle on the hole size and element quality after remeshing is experimentally analyzed. Secondly, the grid sources for element size control are attached to moving bodies and will move along with their host bodies to ensure reasonable grid resolution inside the hole. Thirdly, the boundary recovery procedure of a Delaunay grid generation approach is enhanced by a new grid topology transformation technique (namely shell transformation) so that the new grid created inside the hole is therefore free of elements of extremely deformed/skewed shape, whilst also respecting the hole boundary. The proposed local remeshing algorithm has been integrated with an in-house unstructured grid-based simulation system for solving moving boundary problems. The robustness and accuracy of the developed local remeshing technique are successfully demonstrated via industry-scale applications for complex flow simulations. ARTICLE HISTORY

Section: Introductionmentioning

confidence: 99%

An improved local remeshing algorithm for moving boundary problems

Chen

Engineering Applications of Computational Fluid Mechanics

et al. 2016

WIT Transactions on Engineering Sciences, Vol 52

“…The 6DOF motion model requires additional information to determine how the body moves, based on physical properties and forces [5]. This is achieved through the general equations of unsteady motion.…”

Section: Equation Of Chimera Grid Motionmentioning

confidence: 99%

Simulation of unsteady muzzle flow of a small-caliber gun

Dayan¹,

Touati²

2006

The present paper presents a simulation of a firing process of a 7.62mm bullet and muzzle flow out of a gun barrel. The calculation is made in two stages. First, an internal ballistics (IB) simulation via the IBHVG2 software package, is performed in order to obtain bullet travel dependent breech pressure and temperature. Following this, a simulation of unsteady muzzle flow is made, beginning at the start of bullet motion and ending one meter beyond the muzzle exit point. The second stage calculation is carried out via the CFD-FASTRAN finite volume solver package. The movement of the bullet is simulated by a chimera overset meshing technique. In general, there exists very good agreement between the computed IB and the measured muzzle velocity and pressures, and between the CFD precursors flow field, main propellant flow field calculations and the experimental shadowgraph results.

“…The use of overset adaptive Cartesian and prismatic grids has the potential of handling arbitrary We are now in the process of extending an automated hole-cutting algorithm developed for structured grids to overset adaptive Cartesian and prismatic grids to perform hole-cutting [22].…”

Section: Automated Hole Cutting and Donor Cell Identificationmentioning

confidence: 99%

Simulation of Moving Boundary Flow Using Overset Adaptive Cartesian/Prism Grids and DES

Wang¹

2003

The public reporting burden for this collection of information is estimated to average 1 hour per response, includ gathering and maintaining the data needed, and completing and reviewing the collection of information. Send comr of information, including suggestions for reducing the burden, to Department of Defense, Washington Head (0704-0188), 1215 Jefferson Davis Highway, Suite 1204, Arlington, VA 22202-4302. Respondents should be a subject to any penalty for failing to comply with a collection of information if it does not display a currently valid OIV, Development of improved weapon systems requires better understanding of the complex aerodynamics created by moving boundaries. Carriage and release of conventional weapons from aircraft and aerial refueling fall in this category. The flow problems involving moving boundaries are very challenging to compute because the resultant flow field is intrinsically unsteady. Modeling such flow problems is made even more difficult due to the complex geometries and the highly turbulent namre of the unsteady flows. Under an exploratory grant from the AEOSR, a new simulation environment for moving boundary problems is being developed. This environment is designed to advance the state-of-the-art for moving boundary flow problems in the following areas: I. Improve the solution accuracy and efficiency through the use of overset adaptive Cartesian/prism grids. Key flow features will be automatically captured with solution based grid adaptations; 2. Improve the accuracy for highly turbulent unsteady separated flows encountered in moving boundary problems with a hybrid RANS/LES (Reynolds Averaged Navier Stokes/Large Eddy Simulation) approach named Detached Eddy Simulation (DES The report documents the research activities carried out since the grant award, and outlines future work. PLEASE DO NOT RETURN YOUR FORM TO THE ABOVE ADDRESS. AFRL-SR-AR-TR-04- SPONSOR/MONITOR'S ACRONYM(S) SPONSOR/MONITOR'S REPORT NUMBER(S) DISTRIBUTION/AVAILABILITY STATEMENT