A potential flow model is used to study the unsteady flow past two airfoils in configuration, each of which is suddenly set into motion. The airfoil bound vortices are modeled using lumped vortex elements and the wake behind the airfoil is modeled by discrete vortices. This consists of solving a steady state flow problem at each time-step where unsteadiness is incorporated through the “zero nor...

The proper orthogonal decomposition (POD) has been widely used in fluid dynamic applications for extracting dominant flow features. The “gappy” POD is an extension to this method that allows the consideration of incomplete data sets. In this paper, the gappy POD is extended to handle unsteady flow reconstruction problems, such as those encountered when limited flow measurement data is available...

In this paper, the problem of unsteady stagnationpoint flow and heat transfer induced by a shrinking sheet in the presence of radiation effect is studied. The transformed boundary layer equations are solved numerically by the shooting method. The influence of radiation, unsteadiness and shrinking parameters, and the Prandtl number on the reduced skin friction coefficient and the heat transfer c...

The vortex stretching process is relevant to energy transport at various scales in turbulent flow and in vortex reconnection. For these, reasons, exact solutions for vortex flow are useful. Robinson and Saffman [1] examined the Burgers vortex solution and found closed form steady solutions for special parameter values. Unsteady 2D Burgers vortex solutions have been used to model the spanwise st...

Global-stability theory is used to predict the onset of flow unsteadiness based on steady solutions of the Reynolds Averaged Navier–Stokes equations. The stability problem is formulated for compressible flow at moderately-high Reynolds numbers, using a turbulence model to provide closure for the averaged Reynolds stresses. The approach provides an efficient method for predicting the occurrence ...

Experiments are performed in a Mach-6 shock tunnel to examine the laminar-to-turbulent transition process associated with sudden increase surface angle on slender body. A cone/flare geometry 5 $^\circ$ frustum and compression angles ranging from 15 allow range of mean flow configurations, spanning an attached shock-wave/boundary-layer interaction fully separated one; unit Reynolds number is als...

Recent significant improvements to the development of CFD-based unsteady aerodynamic reduced-order models (ROMs) are implemented into the FUN3D unstructured flow solver. These improvements include the simultaneous excitation of the structural modes of the CFD-based unsteady aerodynamic system via a single CFD solution, minimization of the error between the full CFD and the ROM unsteady aerodyna...

Abstract: Enhanced foam flooding is a chemical flooding technology, which is applied to improve the recovery efficiency of oil and gas. The oil displacement agent of enhanced foam flooding is a foam that the polymer and surfactant solution as liquid. In this paper, three-dimensional mathematical model of unsteady flow is established about enhanced foam system in the porous media, and the numeri...