Sloshing in Liquid Storage Tanks with Internal Obstructions
01 Jan 2019-pp 3-12
TL;DR: In this article, the effect of a centrally placed circular obstruction on sloshing frequency and modal mass of annular tanks is studied. But the authors did not consider the effects of a rigid circular obstruction at the center of the tank.
Abstract: In the present paper, the effect of a centrally placed circular obstruction on sloshing frequency and sloshing mass is studied for annular tanks. Finite element approach (ANSYS software) is used to model the liquid. For circular tanks without obstruction, sloshing frequency and sloshing mass at first three modes are obtained using finite element analysis which compare well with the available analytical results. Next, a rigid circular obstruction at the center of tank is modeled and sloshing frequency and modal mass in the first three modes are obtained. It is observed that with the increase in the diameter of the circular obstruction, the sloshing frequency and the percentage of liquid in sloshing mode decrease in first mode. The behavior of these sloshing parameters in higher modes is also discussed. A detailed study over wide range of circular tank geometries is performed. Charts for obtaining sloshing parameters for various tank geometries are plotted.
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TL;DR: In this paper, a review of the sloshing problem in complex tank geometries in form of Intze, elliptical and conical tanks is presented, where the authors present an overview and development of mathematical formulations to predict the sloshhing parameters in the form of convective mass excited and hydrodynamic pressure profiles which enable present structural engineers in designing earthquake resistant storage structures.
Abstract: Post-earthquake utilities of liquid storage tanks do not need any over emphasis. Liquid storage tanks used in public water distribution system provide water for firefighting and also for drinking and household purposes. Tanks used in industry are equally critical as they contain hazardous liquids and their leakage may lead to catastrophic situation. Thus, seismic safety of liquid storage tanks, which are life line structures, is very important. The prime aim of the present work is to review the sloshing phenomenon studied by various researchers in the past. The study is broadly divided into two parts namely tanks without obstruction and tanks with obstruction and its effects on sloshing parameters. A brief review on sloshing problem in complex tank geometries in form of Intze, elliptical and conical tanks is also presented. The study also presents an overview and development of mathematical formulations to predict the sloshing parameters in form of sloshing frequency, convective mass excited and hydrodynamic pressure profiles which enable present structural engineers in designing earthquake-resistant storage structures. A brief review on modeling circular and rectangular liquid storage tanks using ANSYS software is also presented along with the assumptions and suitable element for modeling. The study also investigates the advantages and disadvantages of the different analysis methods available in the finite element program (ANSYS) to obtain the sloshing parameters. The study concludes that an optimum mesh size as detailed in the present study must be evaluated to determine slosh parameters. An arbitrary fine mesh results in a limited number of modes extracted from the finite element analysis and further gives inaccurate solutions.
4 citations
TL;DR: In this paper , a single vertical perforated baffle plate is used as an anti-slosh element with different configurations of perforations to reduce the free surface elevation.
Abstract: The violent dynamic behavior of liquid under horizontal excitation is a key factor that needs to be addressed in the seismic-resistant design of liquid tanks. Therefore, this study focuses on the slosh response of the liquid medium in a rectangular tank under Imperial Valley 1979, El Centro 1940 and Kobe 1995 ground motions of different frequency ranges. The ground motions records are selected based on the PGA/PGV ratio. For slosh control, a single vertical perforated baffle plate is used as an anti-slosh element with different configurations of perforations. Considering the free surface elevation as the major response parameter, the effect of percentage of perforation of the baffle plate, clear spacing of perforations and offset distance of the perforated plate are investigated by carrying out the pressure-based transient analysis using computational fluid dynamic (CFD). The optimum perforation varies from 10% to 17%, corresponding to the frequency of ground motion in the range of far-resonant to near-resonant conditions. Additionally, “rapid zone” ([Formula: see text]-zone) and “moderate zone” ([Formula: see text]-zone) are identified to pilot the positioning of the perforated baffle plate in liquid tanks. The perforated baffle plate with an optimum range of moderately spaced perforations positioned at the moderate zone of the tank effectively reduces the free surface elevation. Furthermore, the perforated baffle plate is more advantageous during violent sloshing under near-resonant conditions.
1 citations
References
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TL;DR: A simplified dynamic analysis is indicated for the response of elevated water tanks to earthquake ground motion.
Abstract: During the Chilean earthquakes of May, 1960, a number of large elevated water tanks were severely damaged whereas others survived without damage. An analysis of the dynamic behavior of such tanks must take into account the motion of the water relative to the tank as well as the motion of the tank relative to the ground. Some simple expressions are given for the pertinent dynamic properties of tanks with free water surface. A simplified dynamic analysis is indicated for the response of elevated water tanks to earthquake ground motion.
586 citations
TL;DR: In this paper, an analysis of the hydrodynamic pressures developed when a fluid container is subjected to horizontal accelerations is presented, and simplified formulas are given for containers having twofold symmetry, for dams with sloping faces and for flexible retaining walls.
Abstract: An analysis is presented of the hydrodynamic pressures developed when a fluid container is subjected to horizontal accelerations. Simplified formulas are given for containers having twofold symmetry, for dams with sloping faces, and for flexible retaining walls. The analysis includes both impulsive and convective fluid pressures.
535 citations
TL;DR: Theoretical and experimental investigations of the dynamic behavior of ground-supported, deformable, cylindrical liquid storage tanks were conducted in this paper, where a detailed theoretical treatment of the coupled liquid-shell system for tanks rigidly anchored to their foundations was presented.
Abstract: Theoretical and experimental investigations of the dynamic behaviour of ground-supported, deformable, cylindrical liquid storage tanks were conducted. The study was carried out in three phases: (I) a detailed theoretical treatment of the coupled liquid-shell system for tanks rigidly anchored to their foundations; (II) an experimental investigation of the dynamic characteristics of full-scale tanks; and (III) a development of an improved seismic design procedure.
255 citations
TL;DR: In this paper, the effects of a rigid baffle on the seismic response of liquid in a rigid cylindrical tank are presented, where the authors assume that fluid motion is irrotational, incompressible and inviscid.
101 citations