Fruit of Islam

About: Fruit of Islam is a based out in . It is known for research contribution in the topics: Wind tunnel & Longitudinal static stability. The organization has 28 authors who have published 32 publications receiving 216 citations.

A Rule-based Approach to Syntactic and Semantic Composition of BOMs

Abstract: Creating simulation models via composition of predefined and reusable components is an efficient way of reducing costs and time associated with the simulation model development process. However, in order to successfully compose models one has to solve the issues of syntactic and semantic composability of components. HLA is the most widely used architecture for distributed simulations today. It provides a simulation environment and standards for specifying simulation parts and interactions between simulation parts. But it provides little support for semantic composability. The base object model (BOM) standard is an attempt to ease reusability and composition of simulation models. However, BOMs do not contain sufficient information for defining concepts and terms in order to avoid ambiguity, and provide no methods for matching conceptual models (state machines). In this paper, we present our approach for enhancement of the semantic contents of BOMs and propose a three-layer model for syntactic and semantic matching of BOMs. The semantic enhancement includes ontologies for entities, event and interactions in each component. We also present an OWLS description for each component including the state- machines. The three-layer model consists of syntactic matching, static semantic matching and dynamic semantic matching utilising a set of rules for reasoning about the compositions. We also describe our discovery and matching rules, which have been implemented in the Jess inference engine. In order to test our approach we have defined some simulation scenarios and implemented BOMs as building blocks for development of those scenarios, one of which has been presented in this paper. Our result shows that the three-layer model is promising and can improve and simplify composition of BOM-based components.

LES of the Flow Past an Inclined 6:1 Prolate Spheroid

Abstract: Flows around maneuvering ships, submarines and underwater vehicles are usually quite complicated, and often experience three-dimensional open flow separation resulting in unsteady forces and moments that may be detrimental to ship performance. The objective of this investigation is to support more applied maneuvering studies by investigating the computational model performance with respect to approaches to flow simulation methodologies, turbulence modeling, grid resolution and the effects of tripping devices often used in experimental studies. To study these issues simulations are performed of the flow past a 6:1 prolate spheroid, tripped at the nose, and experimentally studied in a series of papers by Simpson et al. Here, we compare predictions from Reynolds Averaged Navier Stokes (RANS), Detached Eddy Simulation (DES) and Large Eddy Simulation (LES) models with experimental data. For the LES computations, different subgrid models are utilized and since the experimental study is carried out using a tripped model, a simple trip model is also developed and tested together with the LES models. Large scatter between the predictions is found, with the DES model and one of the trip-ped LES model showing very good agreement with the data. For LES, the modeling of the trip, which is usually not considered, appears as important as that of the near wall handling and modeling in wall-modeled LES.

DES and Hybrid RANS-LES Modelling of Unsteady Pressure Oscillations and Flow Features in a Rectangular Cavity

Abstract: Using the Detached Eddy Simulation (DES) and an algebraic hybrid RANS-LES model, computations are conducted for the flow over a rectangular cavity at a Mach number of M ∞ =0.85. The emphasis is placed on the prediction of unsteady pressure patterns inside the cavity in terms of pressure fluctuations and deduced acoustic tonal modes in comparison with available experimental data. Furthermore, some resolved cavity flow features are also compared, for which a set of wall-resolved LES data is taken as reference. It is shown that both modelling approaches have produced similar results that are in good agreement with experimental or LES data. The DES modelling has generated somewhat reduced pressure fluctuations on the cavity floor. The hybrid model pronounces a less diffusive mixing layer over the cavity opening, which makes a slightly better prediction for the mean flow field.

Transition Prediction and Impact on 3D High-Lift Wing Configuration

Abstract: The evolution of maximum lift coefficient of a transport aircraft as a function of Reynolds number can be linked to modifications of the laminar-turbulent transition process. In the framework of European project EUROLIFT (I), a task was dedicated to the physical understanding and the numerical modeling of the transition process in high-lift configurations. Then, in the follow-on project EUROLIFT II, a major step is the integration of transition prediction tools within Reynolds-averaged Navier-Stokes (RANS) solvers in order to estimate the impact of transition on performance. This paper presents an overview of the different activities dealing with transition in the EUROLIFT II project.