Faculty Publications
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Item Influence of Geometric Parameters in Self-damping Efficiency of Rectangular Liquid Storage Tanks(Springer Science and Business Media Deutschland GmbH, 2023) Nimisha, P.; Jayalekshmi, B.R.; Venkataramana, K.Turbulent fluctuation of the liquid medium under lateral excitation is a major area of concern due to the potential severities it may cause if the contained structure is damaged.Therefore, this study focuses on variation in the self-damping efficiency of the liquid mass in a liquid tank under lateral excitation.For this, a parametric study has been carried out by changing the aspect ratio of the tank with respect to the horizontal and vertical dimensions.Pressure-based transient analysis has been carried out considering harmonic excitation as well as seismic ground motions.The transient response of the liquid medium is observed in terms of free surface elevation and hydrodynamic pressure.The study reveals that an accurate geometric design of the tank structure improves the self-damping of the sloshing liquid.An aspect ratio of less than ‘1’ results in the improved self-damping efficiency of the contained liquid mass.The effect of the vertical dimension of the tank on slosh damping is less significant compared with that of the horizontal dimension. © 2023, The Author(s), under exclusive license to Springer Nature Singapore Pte Ltd.Item Parametric Study on Frequency Characteristics of Cylindrical Liquid Tanks(Springer, 2022) Nimisha, P.; Jayalekshmi, B.R.; Venkataramana, K.The response of liquid-storage tanks under seismic loading is a key research area. The study of free vibration characteristics is a prerequisite for understanding the dynamic behaviour of liquid tanks under seismic loading. Hence, the present study focuses on the analysis of different parameters that may influence the frequency characteristics of cylindrical liquid tanks. For this, a database of 560 three-dimensional cylindrical liquid tank models was developed by carrying out modal analysis using ANSYS Mechanical APDL software. The database was analysed with the aid of artificial neural networks and nonlinear regression analysis. Average deviations of 30% and 32% were observed for the impulsive frequency values estimated based on IS1893 (Part2):2014 and Eurocode-8, respectively, compared to the finite element results. Hence, modification coefficients were suggested with aspect ratio as the demarcating parameter and obtained a Pearson correlation coefficient of rXY > 0.9, between the predicted values of frequency and actual values. The predicted formulae reduced the deviations observed between the frequency estimated based on the codal expressions and those obtained from finite element analysis to 13% and 15%, corresponding to IS1893 (Part2):2014 and Eurocode-8, respectively. © 2022, The Institution of Engineers (India).Item Slosh Damping in Rectangular Liquid Tank with Additional Blockage Effects under Pitch Excitation(American Society of Mechanical Engineers (ASME), 2022) Nimisha, P.; Jayalekshmi, B.R.; Venkataramana, K.The quantification and damping of slosh responses are significant due to the increasing demand for safety of the liquid-based applications under severe external excitation. Recently, the solid or perforated baffle plates have been used to damp the slosh response of the liquid. However, there is uncertainty in the selection of an effective configuration of the baffle plates. In addition, most of the studies reported the slosh response under surge excitation. Therefore, this study focuses on the slosh response of the rectangular tank fitted with perforated baffle plates of different configurations under pitch excitation. For this, the liquid sloshing is simulated using the concepts of computational fluid dynamics (CFD) using pressure-based solver in the time domain. A detailed parametric study is carried out to develop an effective configuration of the perforated baffle plates considering the area of perforations, interperforation distance, size of perforations, distance between the perforated baffle plates, alignment of perforations, and the vertical position of perforated baffle plate as the parameters. The slosh responses are observed in terms of free surface elevation, hydrodynamic pressure, turbulence kinetic energy, velocity streamlines, power spectral density corresponding to the free surface elevation and the free surface deformation. The study developed a "zig-zag blocking alignment"of perforations for effective slosh damping, with the solid area between the perforations being 50%-60% of the area of perforations. In addition, "single-acting range"and "damping range"are identified to pilot the positioning of the multiple baffle plates in a rectangular tank under pitch excitation. © 2022 by ASME.