Local Study of Jet of a Fluid Sloshing Inside a Rolling Tank

2021 ◽  
Author(s):  
Wen-Huai Tsao ◽  
Spyros Kinnas
Keyword(s):  
2020 ◽  
Author(s):  
Wen-Huai Tsao ◽  
Spyros A. Kinnas

Abstract Sloshing is an important topic for the integrity of LNG tanks and the overall stability of the vessel. In the past, the interaction between the free surface and its substructure have been studied, especially where high-speed fluid jets impinge on the interior surface of the tank, and sometimes cause damage. In this paper, a boundary element method (BEM) with a fourth-order Runge-Kutta scheme is used to study the local phenomenon of nonlinear free-surface motion in a two-dimensional tank subject to roll motions. As the external excitations are nearly resonant with the fluid inside the tank, large free-surface deformations usually take place. The dynamic responses including the fluid velocity and pressure will grow drastically as the fluid is slamming on the walls. If no adequate conditions are applied, it is difficult to capture the peak physical quantities associated with strong nonlinear waves by most conventional Eulerian-Lagrangian methods. The numerical error will be accumulated and enlarged in just a few computational steps, which will eventually lead to unstable solutions. This paper will study the local phenomenon of a fast-moving jet forming on the wall of the tank, and its effect on the numerical stability and accuracy of the method overall. Some special numerical treatments are carried out for the local phenomenon approximation. The conservation of fluid mass is employed to obtain a reasonable geometry of the jet and its velocity along the wall. This provides a new set of rational boundary conditions applied on the walls, rather than using the artificial damping effect of other researchers. Results from the present method are compared with those from the volume of fluid (VOF) method implemented in ANSYS Fluent. The local free-surface shape in the vicinity of the jet and some local and global flow field patterns, including velocity and pressure, will be compared with and verified with experimental observations and measurements.


2020 ◽  
Vol 23 (18) ◽  
Author(s):  
Waleed Nassar Jaffa ◽  
Duraid Taha Abdulkareem ◽  
Ehab Jasim Mohammad
Keyword(s):  

2020 ◽  
Vol 2020 ◽  
pp. 1-14
Author(s):  
Chunhui Wang ◽  
Chunyu Guo ◽  
Fenglei Han

Modified 3D Moving Particle Semi-Implicit (MPS) method is used to complete the numerical simulation of the fluid sloshing in LNG tank under multidegree excitation motion, which is compared with the results of experiments and 2D calculations obtained by other scholars to verify the reliability. The cubic spline kernel functions used in Smoothed Particle Hydrodynamics (SPH) method are adopted to reduce the deviation caused by consecutive two times weighted average calculations; the boundary conditions and the determination of free surface particles are modified to improve the computational stability and accuracy of 3D calculation. The tank is under forced multidegree excitation motion to simulate the real conditions of LNG ships, the pressures and the free surfaces at different times are given to verify the accuracy of 3D simulation, and the free surface and the splashed particles can be simulated more exactly.


2019 ◽  
Vol 123 (17) ◽  
pp. 10849-10856 ◽  
Author(s):  
Alberto Battistel ◽  
Christopher R. Dennison ◽  
Andreas Lesch ◽  
Hubert H. Girault

Author(s):  
Ashley Clark ◽  
Matthew Walker ◽  
Kyle Wetzlar ◽  
Stephen Choi ◽  
James Coe ◽  
...  
Keyword(s):  

2014 ◽  
Vol 13 (08) ◽  
pp. 1450057 ◽  
Author(s):  
Maria-Laura Torrente ◽  
Mauro C. Beltrametti

We consider the problem of deciding whether or not an affine hypersurface of equation f = 0, where f = f(x1, …, xn) is a polynomial in ℝ[x1, …, xn], crosses a bounded region 𝒯 of the real affine space 𝔸n. We perform a local study of the problem, and provide both necessary and sufficient numerical conditions to answer the question. Our conditions are based on the evaluation of f at a point p ∈ 𝒯, and derive from the analysis of the differential geometric properties of the hypersurface z = f(x1, …, xn) at p. We discuss an application of our results in the context of the Hough transform, a pattern recognition technique for the automated recognition of curves in images.


2021 ◽  
Vol 21 (1) ◽  
Author(s):  
Sarah Marshall ◽  
Sarah Taki ◽  
Penny Love ◽  
Yvonne Laird ◽  
Marianne Kearney ◽  
...  

Abstract Background Behavioural interventions for the early prevention of childhood obesity mostly focus on English-speaking populations in high-income countries. Cultural adaptation is an emerging strategy for implementing evidence-based interventions among different populations and regions. This paper describes the initial process of culturally adapting Healthy Beginnings, an evidence-based early childhood obesity prevention program, for Arabic and Chinese speaking migrant mothers and infants in Sydney, Australia. Methods The cultural adaptation process followed the Stages of Cultural Adaptation theoretical model and is reported using the Framework for Reporting Adaptations and Modifications-Enhanced. We first established the adaptation rationale, then considered program underpinnings and the core components for effectiveness. To inform adaptations, we reviewed the scientific literature and engaged stakeholders. Consultations included focus groups with 24 Arabic and 22 Chinese speaking migrant mothers and interviews with 20 health professionals. With input from project partners, bi-cultural staff and community organisations, findings informed cultural adaptations to the content and delivery features of the Healthy Beginnings program. Results Program structure and delivery mode were retained to preserve fidelity (i.e. staged nurse calls with key program messages addressing modifiable obesity-related behaviours: infant feeding, active play, sedentary behaviours and sleep). Qualitative analysis of focus group and interview data resulted in descriptive themes concerning cultural practices and beliefs related to infant obesity-related behaviours and perceptions of child weight among Arabic and Chinese speaking mothers. Based on the literature and local study findings, cultural adaptations were made to recruitment approaches, staffing (bi-cultural nurses and project staff) and program content (modified call scripts and culturally adapted written health promotion materials). Conclusions This cultural adaptation of Healthy Beginnings followed an established process model and resulted in a program with enhanced relevance and accessibility among Arabic and Chinese speaking migrant mothers. This work will inform the future cultural adaptation stages: testing, refining, and trialling the culturally adapted Healthy Beginnings program to assess acceptability, feasibility and effectiveness.


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