The sound generated by a vortex pair moving close to rectangular cylinder is studied high-resolution simulations of the two-dimensional unsteady compressible Navier-Stokes equations at Mach numbers ranging from 0.05 0.3. In this study, number Ma defined Ma=Vt /c0, where Vt translation velocity co-moving and c0 denotes speed sound. directly computed far-field compared prediction acoustic analogy...

This paper gives rigorous numerical analysis of the error in prediction of aeroacoustic noise via Lighthill analogy. The first fundamental and intractable problem is to predict the sound power on surfaces. We give a full analysis of three methods of prediction. The second fundamental problem is the limited regularity of the underlying turbulent flow. This is handled herein by giving a negative ...

Aerodynamic noise from a wind turbine is numerically modeled in the time domain. An analytic trailing edge noise model is used to determine the unsteady pressure on the blade surface. The far-field noise due to the unsteady pressure is calculated using the acoustic analogy theory. By using a strip theory approach, the two-dimensional noise model is applied to rotating wind turbine blades. The n...

Recently, there has been a surge of interest in nonequilibrium collective quantum models, where particle dispersion and spin are examples of effects taken into account. Here, we derive a kinetic plasma model containing fermion exchange effects. Exchange interactions are of great importance in many systems and have no classical analogy. Our model therefore constitutes a possible probe of collect...

thinkers and philosophers have constantly benefited from different         approaches of reasoning to explore and justify their ideas. theses reasoning            approaches are considered as the principle instruments in speculative activities of the thinkers. to this end to achieve the procedure of thinking and the way philosophers achieve objectives, it is necessary to recognize their reasoni...

This study investigates the effects of grid resolution on hydroacoustic performance benchmark INSEAN E779A propeller operated in uniform flow, open water and non-cavitating conditions. In numerical calculations, an incompressible hydrodynamic solver together with porous FW-H (Ffowcs-Williams Hawkings) equation is used to predict URN (Underwater Radiated Noise). The first aim within this explore...

acoustic neuromas (an) are schwann cell-derived tumors that commonly arise from the vestibular portion of the eighth cranial nerve also known as vestibular schwannoma(vs) causes unilateral hearing loss, tinnitus, vertigo and unsteadiness. in many cases, the tumor size may remain unchanged for many years following diagnosis, which is typically made by mri. in the majority of cases the tumor is s...

Abstract Two rotating blade models with different half-flat tip trailing edge serrations were proposed. The flow characteristics and aerodynamic noise simulated using the large-eddy simulation model Ffowcs Williams Hawking’s acoustic analogy, respectively. effect of in reducing was investigated. Results showed that proposed serration designs can effectively reduce broadband noise, effectiveness...

Electron material waves cannot permeate a periodic atomic lattice at each energy or frequency. There exists forbidden gap due to the periodicity of atoms. In analogy, acoustic penetrate phononic sonic crystal A two-dimensional consists cylinders. The is adjusted according wavelength sound. Depending on frequency, there exist “allowed” bands with propagation as well “forbidden” band without corr...