Vol.3, No 15, 2003 pp. 973-980
UDC 532.546
Invited Paper

COMPRESSIBLE CHANNEL FLOW
OVER A PERMEABLE WALL
Vladan D. Djordjević
Professor, University of Belgrade, Faculty of Mechanical Engineering
27. marta 80, 11120 Belgrade, Serbia and Montenegro
E-mail: vdjordjevic@mas.bg.ac.yu

Abstract. The problem of 2-D compressible gas flow through a channel with one permeable wall, which makes the part of the contour of a porous body, is treated in the paper as the problem of strong interaction between the channel flow and the flow through the porous body. Simplified equations governing both flows are solved by using matching conditions on the permeable wall, whereby the need for using empirically defined slip boundary conditions by Beavers and Joseph is eliminated. Slip velocity is found to increase down the channel attaining its maximum value, equal to the value for an incompressible fluid, at the exit cross section of the channel. Exact expressions for the friction coefficient and the relative increase of the mass flow rate due to the slip are derived, and better agreement with the existing experiments is shown to take place than by using the concept of slip boundary conditions.
STRUJANJE STIŠLJIVOG GASA
KROZ KANAL SA POROZNIM ZIDOM
Ravansko strujanje stišljivog gasa kroz kanal sa jednim poroznim zidom, koji čini deo konture nekog poroznog tela, tretira se u radu kao problem jake interakcije izmedju strujanja u kanalu i strujanja kroz porozno telo. Pojednostavljene jednačine kojima se opisuju oba strujanja rešene su korišćenjem uslova spajanja na poroznom zidu, pri čemu se eliminiše potreba za korišćenjem uslova klizanja fluida koji su empirijski definisali Beavers i Joseph. Pronadjeno je da brzina klizanja raste u pravcu strujanja i da dostiže svoju maksimalnu vrednost u izlaznom preseku kanala. Ta vrednost je jednaka onoj koja se ima kod strujanja nestišljivog fluida. U radu su izvedene tačne vrednosti  koeficijenta trenja i relativnog povećanja masenog protoka kroz kanal, izazvanog proklizavanjem fluida duž poroznog zida. Dobijeni rezultati bolje se slažu sa postojećim eksperimentima, nego u slučaju korišćenja graničnog uslova klizanja.