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In order to optimize the balance between aerodynamics and air-cooling performances for a motorcycle, a simulation method of external flow around a vehicle has been developed. In this paper, steady-state flow calculations were performed using two types of turbulence models, the realizable k-ε and the SST k-ω , and two levels of mesh sizes of computational models and their results were compared. To validate the computational results, wind tunnel tests were conducted and CD, CL and mean velocity of flow passing through heat exchangers were measured. The computational results on drag coefficient...
Partially–premixed combustion occurs in many combustion devices of practical interest, such as gas–turbine combustors. Development of corresponding turbulent combustion models is important to improve the design of these systems in efforts to reduce fuel consumption and pollutant emissions. Turbulent lifted flames have been a canonical problem for testing models designed for partially–premixed turbulent combustion. In this paper we propose modifications to the coherent flame model (CFM) so that it can be brought to the simulation of partially-premixed combustion. For the primary premixed flame...
Simulations using CFD and chemical kinetics models have been applied to gain a better understanding of the effect of the recirculated gases on the autoignition process during cold starting of a direct injection diesel engine. The cranking gases recirculated (CGR) contain fuel vapor and partial oxidation products which affect the autoignition process in different ways. Some hydrocarbons (HCs) species enhance the reaction rates and reduce ignition delay. Meanwhile other HCs species and the partial oxidation products of the autoignition process have an opposing effect. The simulation covered a...
The aim of the presentation is to demonstrate the possibilities of predicting loads on partially submerged, moving structures, in particular on tanks in ships and on offshore platforms. Since tanks can in reality move arbitrarily, we are using the moving grid approach and a Finite Volume solution method designed to cater for arbitrary motions of polyhedral control volumes. The motion of liquid is computed using an interface-capturing scheme which allows overturning and breaking of waves. By performing a coupled simulation of the flow and vessel motion, it is possible to obtain a realistic...
Thisstudy is focused on the simulation of open channel turbulentflow over flooded laboratory scale bridge decks and formation ofscour holes under various flooding conditions. Solutions for turbulent flowfield are based on Reynolds Averaged Navier-Stokes (RANS) equations andturbulence closure models using the STAR-CD commercial computational fluid dynamics(CFD) software. An iterative computational methodology is developed for predictingequilibrium scour profiles using the single-phase flow model with amoving boundary formulation. The methodology relies on an empirical correlationfor critical...
Recent development of numerical methods for a coupled simulation of fluid flow and flow-induced motion of rigid bodies have made it possible to simulate launching of lifeboats from offshore platforms or marine vessels, taking into account all relevant details of the geometry, the wind and the waves. One such method developed by authors and coworkers is described, and an example of simulation of lifeboat launching under storm conditions is presented. It is shown that by using overlapping grids and local mesh refinement, one can perform a simulation covering 6 s of real time on a single...
The paper describes results of computations of resistance, trim and sinkage for the KRISO Container Ship (KCS) at different Froude numbers in calm water. Unstructured trimmed grids with local refinement in zones of interest have been used to obtain maximum accuracy at low cell count. The solution method is of finite-volume type and uses mostly approximations of second order. Free surface is modeled using Volume-of-Fluid approach and a high-resolution interface-capturing scheme. It is demonstrated that acceptable accuracy can be achieved with grids containing around half a million cells for...
Aerodynamic performance of racing bicycles and practical considerations for CFD workflows
As CFD is being embraced by the frame, wheel and component manufacturers in the cycling industry, some practical challenges are quickly emerging. Discussions and concerns regarding the scope and resources required to conduct CFD studies, as well as their relevance, are quickly evolving - a phenomenon which is not unique to the cycling community. In this presentation we will outline a process, that can effectively help to manage CFD in the overall design process by directly addressing data management and workflow issues. Particularly we see a tremendous opportunity for cycling manufacturers,...
The present work describes the numerical simulation of a sonic nozzle performed by a commercial numerical code. The main objective of the work was to assess the reliability of such codes as tools for metrological work. The paper briefly describes the background of numerical simulation of fluid flows, and recalls the main formulations of common use in sonic nozzle analysis. The results show that, for a test case with a well-defined geometry and relatively simple boundary conditions, commercial CFD codes can be a useful support tool for metrological analysis.

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