01592nas a2200205   4500008004100000022001400041245009700055210006900152260009200221300001400313490000800327520080200335653001801137653001501155653002101170653002501191100002001216700002201236856012801258       2005                        eng d  a0098-644500aCharacterization of gas-liquid flows in rectangular bubble columns using conductivity probes0 aCharacterization of gasliquid flows in rectangular bubble column  a4 PARK SQUARE, MILTON PARK, ABINGDON OX14 4RN, OXON, ENGLANDbTAYLOR & FRANCIS LTDcSEP  a1129-11500 v1923 a<p>Unsteady gas-liquid flows in bubble columns are comprised of various flow processes occurring with varying length and time scales and govern mixing and transport processes. In the present work, we have characterized dynamic and time-averaged properties of gas-liquid flows in rectangular bubble columns using conductivity probes. The development of a single-tip conductivity probe, data processing methodology, and photographic validation procedure is discussed in detail. The effect of superficial gas velocity and aerated liquid height-to-width ( H/W) ratio on voidage fluctuations and time-averaged gas holdup was investigated. The experimental data presented here can help in understanding the dynamics of various flow processes and validating computational fluid dynamics based models.</p>10aBubble column10agas holdup10agas-liquid flows10avoidage fluctuations1 aBuwa, Vivek, V.1 aRanade, Vivek, V.  uhttps://library.ncl.res.in/content/characterization-gas-liquid-flows-rectangular-bubble-columns-using-conductivity-probes-001968nas a2200241   4500008004100000022001400041245008300055210006900138260010600207300001200313490000700325520108500332653001801417653000801435653001301443653003401456653003601490653002001526100002001546700002401566700002201590856011401612       2006                        eng d  a0301-932200aEulerian-lagrangian simulations of unsteady gas-liquid flows in bubble columns0 aEulerianlagrangian simulations of unsteady gasliquid flows in bu  aTHE BOULEVARD, LANGFORD LANE, KIDLINGTON, OXFORD OX5 1GB, ENGLANDbPERGAMON-ELSEVIER SCIENCE LTDcJUL  a864-8850 v323 a<p>We studied the dynamics of gas-liquid flows in a rectangular bubble column using Eulerian-Lagrangian simulations. Three-dimensional, unsteady simulations were performed to simulate the dynamic characteristics of the oscillating bubble plume. The effect of superficial gas velocity and aerated liquid height-to-column width (HI K) ratio on the dynamic and time-averaged flow properties was studied and the simulated results were validated using wall pressure and voidage fluctuation measurements. The effect of lift force and numerical diffusion on the dynamic and time-averaged properties is discussed in detail. Further, the results obtained using the Eulerian-Lagrangian simulations were compared with the Eulerian-Eulerian simulations. The bubble scale information, which is otherwise lost in the Eulerian-Eulerian simulations, was validated using the voidage fluctuation measurements. Such experimentally validated Eulerian-Lagrangian models will be useful for the simulation of mass transfer and reactions in bubble columns. (c) 2006 Elsevier Ltd. All rights reserved.</p>10aBubble column10aCFD10aDynamics10aEulerian-Eulerian simulations10aEulerian-Lagrangian simulations10agas-liquid flow1 aBuwa, Vivek, V.1 aDeo, Dhanannjay, S.1 aRanade, Vivek, V.  uhttps://library.ncl.res.in/content/eulerian-lagrangian-simulations-unsteady-gas-liquid-flows-bubble-columns-001898nas a2200205   4500008004100000245006600041210006600107260010600173300001400279490000700293520119700300653001101497653001801508653001601526653001801542653000801560653001501568100002301583856008601606       2008                        eng d00aExperimental analysis of the lift force on bubbles in a swarm0 aExperimental analysis of the lift force on bubbles in a swarm  aTHE BOULEVARD, LANGFORD LANE, KIDLINGTON, OXFORD OX5 1GB, ENGLANDbPERGAMON-ELSEVIER SCIENCE LTDcOCT  a1710-17230 v633 a<p>The lift force acting on bubbles in a swarm has been estimated by analyzing the instantaneous velocity-time data obtained using LDA in a cylindrical bubble column. Phase distinction was achieved through the multiresolution analysis of the velocity-time data. Several important issues related to the transverse motion of bubbles subjected to a shear field have been discussed quantitatively. The actually measured bubble sizes, the respective slip velocity values in transverse and axial directions and the local shear rates (gamma) enabled the verification of known formulations for the lift coefficient (C-L) for bubbles. At many locations in the column the radial flux of the gas phase by turbulent dispersion and the radial slip were estimated. The radially inward movement of bubbles from low to high axial velocity (from column wall to center, i.e., C-L &lt; 0) was observed at most of the measurement locations. The local lift coefficient was estimated using the transverse drag force and the values support the results from the material balance approach. The estimated C-L values showed a wide variation over the column cross-section. (c) 2007 Elsevier Ltd. All rights reserved.</p>10aBubble10aBubble column10abubble size10ahydrodynamics10aLDA10alift force1 aKulkarni, Amol, A.  uhttps://library.ncl.res.in/content/experimental-analysis-lift-force-bubbles-swarm01902nas a2200253   4500008004100000022001400041245013400055210006900189260010600258300001400364490000700378520091400385653001801299653001601317653000801333653004501341653003601386100002201422700001801444700002101462700002601483700002101509856011801530       2008                        eng d  a0301-932200aSVR-based prediction of point gas hold-up for bubble column reactor through recurrence quantification analysis of LDA time-series0 aSVRbased prediction of point gas holdup for bubble column reacto  aTHE BOULEVARD, LANGFORD LANE, KIDLINGTON, OXFORD OX5 1GB, ENGLANDbPERGAMON-ELSEVIER SCIENCE LTDcDEC  a1099-11070 v343 a<p>Recurrence quantification analysis (RQA) has emerged as a useful tool for detecting singularities in nonstationary time-series data. In this paper, we use RQA to analyze the velocity-time data acquired using laser doppler anemometry (LDA) signals in a bubble column reactor for Single point and Multipoint point spargers. The recurring dynamical states within the velocity-time-series occurring due to the bubble and the liquid passage at the point of measurement, are quantified by RQA features (namely % Recurrence, % Determinism, % Laminarity and Entropy), which in turn are regressed using support vector regression (SVR) to predict the point gas hold-up values. It has been shown that SVR-based model for the bubble column reactor can be potentially useful for online prediction and monitoring of the point gas hold-up for different sparging conditions. (C) 2008 Elsevier Ltd. All rights reserved.</p>10aBubble column10aGas hold-up10aLDA10aRecurrence quantification analysis (RQA)10aSupport vector regression (SVR)1 aGandhi, Ankit, B.1 aJoshi, J., B.1 aKulkarni, A., A.1 aJayaraman, Valadi, K.1 aKulkarni, B., D.  uhttps://library.ncl.res.in/content/svr-based-prediction-point-gas-hold-bubble-column-reactor-through-recurrence-0