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Úplav za Ahmed Body
Uruba, Václav ; Hladík, Ondřej
The Ahmed body is now accepted as a test-case prototype of a typical modern passenger car possessing all typical aerodynamic features – a bluff body with separated boundary layer generating wake resulting into pressure drag. Several types of vortical structures arise in the wake, quasi-stationary and highly dynamic in nature.
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Numerical simulation of jet flow using LES
Louda, Petr ; Kozel, K. ; Příhoda, Jaromír
The work deals with the numerical method for the large eddy simulation (LES) of incompressible flow. Governing system of filtered Navier-Stokes equations is completed by the Smagorinsky turbulence model and the Poisson equation is used for pressure instead of the continuity equation. The numerical method is based on an explicit scheme with fourth order accurate central approximation for convection and resolved diffusion. Preliminary results for the plane turbulent free jet are shown. Problem of the prescription of boundary conditions is discussed in detail.
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Řízení mezní vrstvy na profilu s vychýlenou klapkou pomocí vírových generátorů
Součková, Natálie ; Šimurda, David ; Popelka, Lukáš
The paper focuses on reducing eventually removing flow separation, which is occurred on deflected flap, with vortex generators. Airfoil NACA 63A421 with simple flap and low profile vane-type vortex generators were used. The investigation was carried out using experimental and numerical method. The flow over the airfoil was visualized by tuft filaments technique in closed circuit wind tunnel for two flap deflections and four angles of attack. Two size and two different shapes of vortex generators were tested. The data from numerical simulation of flapped airfoil without VG's control were used for vortex generator designing.
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Změny v pravděpodobnostní distribučni funkci koncentrací pasivní příměsi
Jurčáková, Klára ; Riveron, F.
The scope of this study is to find general description of probability distribution functions (PDF), which describes temporal variation of passive contaminant concentrations released from ground level point source within the atmospheric boundary layer. The Weibull distribution was found to be most suitable form for those PDFs. Two parameters of Weibull distribution were found to be a function of gross time series parameters such mean and standard deviation values of the concentration time series.
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