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Titolo:
ACOUSTIC STREAMING - COMPARISON OF LOW-AMPLITUDE LINEAR-MODEL WITH STREAMING VELOCITIES MEASURED BY 32-MHZ DOPPLER
Autore:
NOWICKI A; SECOMSKI W; WOJCIK J;
Indirizzi:
POLISH ACAD SCI,INST FUNDAMENTAL TECHNOL RES,DEPT ULTRASOUND,SWIETOKRZYSKA 21 PL-00049 WARSAW POLAND
Titolo Testata:
Ultrasound in medicine & biology
fascicolo: 5, volume: 23, anno: 1997,
pagine: 783 - 791
SICI:
0301-5629(1997)23:5<783:AS-COL>2.0.ZU;2-S
Fonte:
ISI
Lingua:
ENG
Keywords:
ULTRASOUND; STREAMING; NONLINEAR ULTRASOUND EFFECTS; DOPPLER;
Tipo documento:
Article
Natura:
Periodico
Settore Disciplinare:
Science Citation Index Expanded
Science Citation Index Expanded
Citazioni:
13
Recensione:
Indirizzi per estratti:
Citazione:
A. Nowicki et al., "ACOUSTIC STREAMING - COMPARISON OF LOW-AMPLITUDE LINEAR-MODEL WITH STREAMING VELOCITIES MEASURED BY 32-MHZ DOPPLER", Ultrasound in medicine & biology, 23(5), 1997, pp. 783-791

Abstract

The pressure gradient along the ultrasonic beam results in medium streaming, Following Nyborg's analysis of the Navier-Stokes equation, Wu and Du developed an approximate solution for the streaming velocity generated by flat and weakly focused transducers. We have modified theirsolution of the Poisson equation by directly deriving the Dirichlet boundary conditions to be applied for this type of equation, Our numerical results (for the linear case) were about one half smaller for hat and weakly focused Gaussian beam transducers compared to the results by Wu and Du, The theoretical calculations were verified using a purpose-designed 32-MHz pulsed Doppler unit, The applied average acoustic power was changed from 1 mu W to 6 mW, the burst width was 0.5 mu s and the pulse repetition frequency was 32 kHz. The experiments were done on il-mm-diameter hat and focused (focal distance = 8 and 12 mm) transducers. The streaming was measured along the ultrasonic beam from 0-20 mm; at all positions, the maximum Doppler frequency was estimated fromthe recorded spectra, Streaming was induced in a solution of water and corn starch, The experimental results showed that, for a given acoustic power, the streaming velocity was independent of the starch density in water changed from 0.3-40 g of starch in 1 l of distilled mater, For applied acoustic powers, the streaming velocity changed linearly from 0,2-40 mm/s, Both the theoretical solutions for plane and focused waves and the experimental results were in good agreement, (C) 1997 World Federation for Ultrasound in Medicine & Biology.

ASDD Area Sistemi Dipartimentali e Documentali, Università di Bologna, Catalogo delle riviste ed altri periodici
Documento generato il 23/09/20 alle ore 15:59:05