The problems of exact state reconstruction and approximate state estimation based on wall information in a wall-bounded incompressible unsteady flow are addressed. It is shown that, if in an arbitrarily small neighborhood of time t precise measurements are made of the two components of wall skin friction and the wall pressure, all terms in the Taylor-series expansions of the unsteady flow state...

To understand the fluid dynamics of a biologically inspired unsteady low-aspect-ratio propulsor, unsteady pressure distributions were measured and compared with time-averaged thrust performance and wake visualizations. The experiments were performed on rigid rectangular panels with different aspect ratios, pitching in a uniform flow. Panel aspect ratio and pitching amplitude were shown to affec...

When a river mouth has a flat converging shape with a tidal range exceeding 6 to 9 m, the river may experience a tidal bore. A tidal bore is a positive surge, and the aim of the study is to detail the turbulent field beneath an undular bore. New unsteady experiments were conducted in a large channel. Turbulence measurements were performed with high-temporal resolution using side-looking acousti...

We consider the numerical simulation of an optimal control problem constrained by the unsteady Stokes-Brinkman equation involving random data. More precisely, we treat the state, the control, the target (or the desired state), as well as the viscosity, as analytic functions depending on uncertain parameters. This allows for a simultaneous generalized polynomial chaos approximation of these rand...

In order to study the creep characteristics of frozen soil under different confining pressures, triaxial tests temperatures are carried out and deformation law pressures freezing is analyzed. this paper, unsteady Abel dashpot constructed by viscosity coefficient. On basis, fractional unsteady. Then, a time-dependent constitutive model for based on established. The can better describe accelerate...

The present study delivers several numerical experiments, conducted on a converging–diverging horizontal nozzle with the insertion of single and multiple circular cylinders. fluid enters from inlet wall, strikes nozzle's cylinder's walls times, affecting entire flow region, and, finally, leaves through outlet wall. This process leads to many new unseen things. lattice Boltzmann method relaxatio...

Several approaches for modelling the longitudinal aerodynamic coefficients of a fighter aircraft at high angles of attack, including the unsteady effects are presented. A traditional approach where the model of the coefficient arises in the form of the steady and unsteady effects, the unsteady effect being modelled by means of transfer functions. The second approach uses an internal variable de...

Numerical simulations of the unsteady flow over a low-aspect-ratio, low Reynolds number semi-circular planform wing are performed using Lattice Boltzmann method. The simulations exactly match the flow conditions and the detailed geometry from previous wind-tunnel experiments, including the flow actuators installed internally along the leading edge of the wing. To reproduce the pulsed-blowing ac...