commit5ea1f8d33c5786f213a03c5a5bb5e304dcb36ea1parent9d4bec0f8c8b341da1203cb9344bf40f49abca50Author:Ivan Gankevich <i.gankevich@spbu.ru>Date:Fri, 13 Mar 2020 13:23:46 +0300 Introduction.Diffstat:

main.tex | | | 47 | ++++++++++++++++++++++++++++++++++++++++++++++- |

1 file changed, 46 insertions(+), 1 deletion(-)diff --git a/main.tex b/main.tex@@ -30,7 +30,7 @@ \email{TODO@student.spbu.ru},\\ \email{i.gankevich@spbu.ru},\\ \email{st016177@student.spbu.ru},\\ -\email{v.khramusin@spbu.ru},\\ +\email{v.khramushin@spbu.ru},\\ \email{st049350@student.spbu.ru}\\ \url{https://spbu.ru/}} @@ -48,6 +48,51 @@ TODO \end{abstract} \section{Introduction} + +Ship motion simulation studies focus on interaction between the ship and ocean +waves~--- a physical phenomena that gives the largest contribution to +oscillatory motion~--- however, intelligent onboard systems require taking +other forces into account. One of the basic functionality of such a system is +determination of initial static ship stability parameters (roll angle, pitch +angle and draught) from the recordings of various ship motion parameters, such +as instantaneous roll, pitch and yaw angles, and their first and second +instantaneous derivatives (e.g.~angular velocity and angular acceleration). +During ship operation these initial static ship stability parameters deviate +from the original values as a result of moving cargo between compartments, +damaging the hull, compartment flooding etc. These effects are especially +severe for fishing and military vessels, but can occur with any vessel +operating in extreme conditions. + +Intelligent onboard system need large amount of synchronous recordings of ship +motions parameters to operate, mainly angular displacement, velocity and +acceleration and draught, but these parameters depend on the shape of the ship +hull and obtaining them in model tests is complicated, let alone field tests. +Field tests are too expensive to perform and do not allow to simulate +particular phenomena such as compartment flooding. Model tests are too +time-consuming for such a task and there is no reliable way to obtain all the +derivatives for a particular parameter: sensors measure one particular +derivative and all other derivatives have to calculated by numerical +differentiation or integration, and integration has low accuracy for time +series of measurements TODO. The simplest way to obtain those parameters is to +simulate ship motion on the computer and save all the parameters in the file +for future analysis. + +Arguably, the largest contribution to ship motion besides ocean waves is given +by wind forces: air has lesser density than water, but air motion acts on the +area of ship hull which is greater than underwater area due to ship +superstructure. Steady wind may produce non-nought roll angle TODO, and thus +have to be taken into account when determining initial static ship stability +parameters. + +In this paper we investigate how wind velocity field can be simulated on the +boundary and near the boundary of the ship hull. We derive a simple +mathematical model for uniform translational motion of the air on the +above-water boundary of the ship hull. Then we generalise this model to +calculate wind velocity near the boundary still taking into account the shape +of the above-water part of the ship hull. Finally, we measure the effect of +wind velocity on the ship roll angle and carry out computational performance +analysis of our programme. + \section{Methods} \section{Results} \section{Discussion}