Corrugated walls were installed in narrow gas-solid bubbling fluidized bed (CWBFB) enclosures to reduce bubble sizes, improve gas distribution and offer stable operation. Thorough analyses of bed expansion in flat- (FWBFB) and corrugated-wall bubbling fluidized beds were performed for a variety of wall declinations and operating conditions covering a range of corrugation angles, inter-wall clearances (C), initial rest bed heights (H-i) and ratios of gas superficial velocity to minimum bubbling velocity, U-g/U-mb. Bed expansion was discriminated in terms of expansion bed height ratio (H-f/H-i) and transport disengagement height (TDH). A digital image analysis technique was employed to compare the behaviors of time-averaged H-f/H-i and TDH in FWBFB and CWBFB. For a given U-g/U-mb, the former was barely affected by wall patterning whereas the latter underwent appreciable reduction in CWBFB compared to FWBFB. Regardless of wall shape, both H-f/H-i and TDH increased with increasing U-g/U-mb and C and with decreasing H-i. Full 3-D transient Euler-Euler CFD simulations with kinetic theory of granular flow employed to simulate the solids volume fraction and granular temperature in FWBFB and CWBFB reached qualitative agreements with experimental findings. (C) 2012 Elsevier Ltd. All rights reserved.