The effect of ambient turbulence intensity on the flow induced oscillations rigid circular cylinders with symmetric and asymmetric local stimulation is studied. Cylinders oscillate in one degree freedom transversely to a steady uniform flow. Two-dimensional unsteady Reynolds-Average Navier-Stokes equations Spalart-Allmaras model are used solve problem numerically. Three freestream values (0.2%,...

The optimal placement of sensors for the estimation of turbulence model parameters in computational fluid dynamics is presented. The information entropy (IE), applied on the posterior uncertainty of the model parameters inferred from Bayesian analysis, is used as a scalar measure of uncertainty. Using an asymptotic approximation, the IE depends on nominal values of the CFD model and prediction ...

Abstract The blended-wing body is an aircraft configuration that has the potential to be more efficient than conventional large transport aircraft configurations with the same capability. However, the design of the blended-wing is challenging due to the tight coupling between aerodynamic performance, trim, and stability. Other design challenges include the nature and number of the design variab...

This paper presents an original approach regarding the application of sweep to rotating blade cascades. The justification for swept blades is given by its consequence, i.e. a reduction of local velocity (usually from supersonic/ transonic to subsonic regimes) such that the losses due to shock waves and/or boundary layer displacement and/or followed by reattachment are minimized. As study cases ...

This study presents an extension of a previous (On Exact Step Length in Gradient-Based Aerodynamic Shape Optimization) to viscous transonic flows. In this work, we showed that the same procedure derive explicit expression for exact step length βexact gradient-based optimization method inviscid flows can be employed The extended numerical was evaluated over RAE 2822 airfoil at two common flow co...

Numerical investigation was performed on NACA 0015 which is a symmetric airfoil. Pressure distribution and then lift and drag forces are verified. Changing of ground clearance was a considerable point. Also the angle of attack was changed from 0° to 10°. Pressure coefficient reaches its higher amounts on the wing lower surface when the ground clearance diminishes. Increment of the angle of atta...

Numerical simulations of the flow surrounding particle agglomerates were carried out using computational fluid dynamics to assess ability five RANS turbulence models estimate drag coefficient in agglomerates. Simulations steady conditions for Reynolds numbers between 1 and 1500. Streamlines showed that symmetrical present a velocity profile similar single sphere profile. Results both Spalart-Al...

Abstract Feature selection targets for selecting relevant and useful features, is a vital challenge in turbulence modeling by machine learning methods. In this paper, new posterior feature method based on validation dataset proposed, which an efficient universal complex systems including turbulence. Different from the priori importance ranking of filter exhaustive search subset wrapper method, ...

The effects of elastic cavity walls on noise generation at transonic speed are investigated for the generic M219 cavity. flow is simulated with Spalart–Allmaras (SA) improved delayed detached-eddy simulation (IDDES) turbulence model in combination a wall function. structural analysis software uses modal formulation. first 50 normal mode shapes included simulation, spanning frequencies 468–2280 ...

Abstract This paper compares the performance of four low-Reynolds-number models for the unsteady Reynolds-averaged Navier-Stokes equations applied to the flow in a channel driven by a pressure gradient oscillating around a non-zero mean. The models considered are the one-equation Spalart-Allmaras model, the k − ε model with the wall functions of Lam and Bremhorst, the k−ω model of Saffman and W...