Two-phase gas±liquid ¯ow in horizontal corrugated channels M. Gradeck*, M. Lebouche LEMTA CNRS UMR 7563. 2 Avenue de la ForeÃt de Haye. BP 160, F-54504, Vandoeuvre Cedex, France Received 10 February 1997; received in revised form 24 February 1999 Abstract Experiments have been carried out for adiabatic concurrent gas±liquid ¯ow of nitrogen and water through two corrugated test sections. This study examines ¯ow patterns as the gas ¯uxes are increased. At low gas ¯uxes two main patterns have been observed: strati®ed ¯ow for low liquid ¯uxes and bubble ¯ow for greater ones. The mean wall shear stress of the two-phase ¯ow has been measured with the electrochemical method (polarography); its analysis reveals the ¯ow structure modi®cation from monophasic to two-phase ¯ow. # 2000 Elsevier Science Ltd. All rights reserved. 1. Introduction Most of the gas±liquid studies involved large circular tubes because it is the most appropriate geometry which can withstand the high pressure. However, these past 30 years, the two-phase gas±liquid ¯ow inside compact heat exchangers received much more attention from the scienti®c community. The technological progress allowed welding of the plates, so that the plate heat exchangers can withstand high pressure and high temperature (6008C). A clear understanding of the eects of corrugated channels on gas±liquid ¯ow is essential to improved design procedures. Hugonnot et al. (1989) have carried both numerical and experimental work on the monophasic newtonian ¯ow in corrugated geometries. Bereiziat (1993) analyses the ¯ow of complex ¯uids. Gradeck and Lebouche (1998) investigate adiabatic International Journal of Multiphase Flow 26 (2000) 435±443 0301-9322/00/$ - see front matter # 2000 Elsevier Science Ltd. All rights reserved. PII: S0301-9322(99)00018-X www.elsevier.com/locate/ijmulflow * Corresponding author.