S U M M A R YDeep seismic sounding data were acquired in the West Bengal basin, India, along two profiles: (i) Bishnupur-Palashi-Kandi, along a line about 227 km long in the northsouth direction and (ii) Taki-Arambagh, along a line about 120 km long in the east-west direction. Seismic refraction and wide-angle reflection data were recorded by continuous profiling using two 60-channel digital seismic units (DFS-V) with an 80 m geophone group interval and 4 ms sampling rate. These data were interpreted in order to delineate the basement configuration. The 2-D models of the seismic data both indicate a five-layer velocity structure above the Archaean crystalline basement (5.9-6.2 km s-I). A low-velocity layer (4.0 km s-') is inferred immediately above the basement in the shelf region of the basin corresponding to the Gondwana sediments (Upper Carboniferous to Lower Triassic) below the Rajmahal Traps (Upper Jurassic to Lower Cretaceous) of 4.6 to 4.8 km s-' velocity, which is also confirmed from the nearby well data. The results along the Taki-Arambagh profile and the drilling results at the Jaguli (J-1) well are used to investigate whether Gondwana sediments and the Rajmahal Traps exist in the deep part of the Bengal basin. An additional layer of velocity 5.2-5.3 km s-', delineated in the Palashi-Kandi profile overlying the basement, may correspond to the Singhbhum group of rocks of the Proterozoic.A structural contour map of the basement prepared from the present results indicates a south-easterly dip of the basement in general. The depth of the basement on the stable shelf of the basin gently increases to about 8 km and dips steeply, plunging to a maximum depth of 14 km in the deep basin. No structural high that can be related to the 'Calcutta gravity high' is found in the basement around the Hooghly River.

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Extensive numerical simulations of the 2-D laminar flow of power-law fluids over elliptical cylinders with different aspect ratios have been carried out to establish the conditions for the onset of wake formation and the onset of vortex shedding. The continuity and momentum equations were solved numerically using FLUENT (version 6.3.26). The influence of the power-law index (0.3 ≤ n ≤ 1.8) and the aspect ratio (E = b/a; 0.2 ≤ E ≤ 5) of the cylinder on the critical values of the Reynolds number denoting the onsets of flow separation and vortex shedding are presented. For shear-thinning (n < 1) fluid behavior, the onsets of wake formation and vortex shedding are both seen to be postponed to higher Reynolds numbers as compared to those in shear-thickening fluids (n > 1). Also, the values of the Strouhal number (St c) and the time-average drag coefficient (C̅ D) corresponding to the cessation of the steady-flow regime are presented. Velocity vector plots denoting the flow separation and vorticity profiles showing the vortex shedding are also included. The delineation of different flow regimes also helps identify the range of validity of some of the results on flow and heat transfer available in the literature.

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The characteristic variation of critical heat flux (CHF) with heater diameter in the pool‐boiling of horizontal cylinders is discussed. Critical heat flux expressions have been obtained based on hydrodynamic considerations for saturated pool‐boiling of cylinders and are compared with existing and new data. Experimental studies are reported which verify the postulated mechanics of the boiling process at CHF over a range of cylinder diameters.