Submerged Floating Tunnel: Water-Structure Interaction

Master thesis (2019)

Authors

D. Popov Civil Engineering & Geosciences

Contributors

Hans Bihs Norwegian University of Science and Technology (NTNU) (mentor)
Arun Kamath Norwegian University of Science and Technology (NTNU) (graduation committee member)
Weizhi Wang Norwegian University of Science and Technology (NTNU) (coach)
Faculty
Civil Engineering & Geosciences, Civil Engineering & Geosciences
Copyright: © 2019 Daniil Popov
More Info
expand_more

Published Date

11-08-2019

Language

English

Reuse Rights

Other than for strictly personal use, it is not permitted to download, forward or distribute the text or part of it, without the consent of the author(s) and/or copyright holder(s), unless the work is under an open content license such as Creative Commons.

Faculty

Civil Engineering & Geosciences

Abstract

This study focuses on water-structure interaction of submerged floating tube in homogeneous and stratified flows, as well as gravity current development. The latter was done in order to set up and validate numerical model that treats water stratification properly and in a computationally efficient manner.
First part of the study is dedicated to gravity current development. Grid convergence study was performed for simulation of two-dimensional gravity current, which showed that optimal cell sizes for the problem in question are 5 mm and 2.5 mm. In addition, Large-Eddy Simulation (LES) model of turbulence was tested, and its performance in simulation was compared to performance of simulation without any turbulence modelling. It was established that the latter represents gravity current development in two dimensions more accurately. After that, gravity current development in three dimensions was performed with LES modelling of turbulence and without any turbulence model. Both simulations were in good agreement with results of physical experiments, therefore LES model is a preferable choice as it is less computationally demanding.
In second part of the project, rigidly fixed horizontal cylinder in flow was considered in order to investigate in-line forces, acting upon the cylinder. At first, model with homogeneous flow was set up and validated. It was established that two-dimensional model with cell size of 2.5 mm and CFL criterion of 0.3 is a good choice in terms of balance between accuracy and computational efficiency. After that, system of two cylinders with varying distance between them was tested. It was established that in-line forces for both cylinders are affected, with influence on the second cylinder being more stark.
Third part of the study is dedicated to horizontal cylinder in stratified flow. Parameters of produced internal waves were in agreement with results of physical experiments.