A synthetic jet can be produced over broad range of time and length-scales. Theirs unique attributes make them attractive fluidic actuators for various flow-control tasks. Generation, evolution and interaction of synthetic jets are reviewed in the presented paper. Application of this actuator type ranging from separation and turbulence control, control to thrust vectoring and mixing augmentation to skin friction control is shown. and Obsahuje seznam literatury
We consider a special dilatant fluid model for which the apparent viscosity can be expressed as a polynomial in the second scalar invariant of the rate of strain tensor. The model has been used to investigate the steady plane Couette flow of a non-Newtonian fluid through a channel with suction, assumed small, at the lower porous wall. The introduction of a similarity transformation in the perturbed governing partial differential equations of the flow leads to a system of coupled non-linear ordinary differential equations. The solutions of these equations have been obtained analytically as a power series in the suction parameter . The combined effects of the non-Newtonian and the suction parameters on the longitudinal and transverse velocity profiles as well as the skin friction, have been discussed. The validity of the analytical solutions has also been checked with the corresponding numerical solutions for small values of the governing parameters. and Štúdia sa zaoberá sa špeciálnym modelom nenewtonskej tekutiny, pre ktorú sa môže skutočná viskozita vyjadriť vo forme polynomickej závislosti na druhom skalárnom invariante tenzora rýchlosti deformácie. Model bol využitý na štúdium ustáleného Couetteho rovinného prúdenia nenewtonskej tekutiny v kanáli so saním cez porézne steny. Zavedenie transformácie podobnosti do lineanizovaných parciálnych diferenciálnych rovníc vedie k systému obyčajných nelineárnych diferenciálnych rovníc. Ich riešenie sme získali vo forme potenčného radu od sacieho parametra λ. Analyzovali sme vplyv rozťažnosti tekutiny a sacieho parametra na pozdĺžny a priečny rýchlostny profil, ako aj na povrchové trenie. Platnosť analytického riešenia sme porovnali s numerickým riešením pre malé hodnoty použitých parametrov.
The induced unsteady flow due to a stretching porous surface in a rotating fluid, where the unsteadiness is caused by the suddenly stretched surface is studied in this paper. After a similarity tranformation, the unsteady Navier-Stokes equations have been solved numerically using the Adams Predictor Corrector Method. It is found that there is a smooth transition from the small time solution to the large time or steady state solution. and Obsahuje seznam literatury a názvosloví