| Author | Sutat Weesakul |
| Call Number | AIT Diss. no. WA-86-04 |
| Subject(s) | Water waves
|
| Note | A dissertation submitted in the partial fulfillment of the requirements for the degree of Doctor of Engineering, School of Engineering and Technology |
| Publisher | Asian Institute of Technology |
| Series Statement | Dissertation ; no. WA-86-04 |
| Abstract | A number of theoretical studies have been conducted on various aspects
of wave-current interactions. Only few studies have concentrated on the
microscopic point of view which is essential for clear understanding of such phenomena.
In this study, the changes of wave characteristics by a current are
solved theoretically for any profile of current velocities up to the third
order using a so-called perturbation method. It is found that a
velocity gradient of unsteady component is negative near the bed in case of a strong vorticity opposing current. When viscosity is employed,
wave-current friction factors defined in ' terms of the shear velocity corresponded to the maximum bed shear stress are de rived implicitly for both
laminar and turbulent flows . The assumption of .the t wo-layer
time-invariant eddy viscosity is modified for ·turbulent flow.
A simple regime of flow for wave-current interaction is proposed under
an assumption of the abrupt change from laminar to turbulent flow. The diagrams showing the relationship between a relative smoothness of the bed and
a flow Reynolds number are presented to indicate the flow regime for given
hydraulic conditions. Experiments are performed to verify the above theories
by measuring the mean current profiles which alter from pure current profiles
due to the influence of wave and current interaction. The experimental results show two types of mean current profiles, increased and r educed velocities which give reasonable agreement with the predicted profiles by the
present theory.
There are many applications for the knowledge of wave-current friction
factor, but only two cases are studied and described in detail, i.e. an energy dissipation and a longshore current model . Lastly a concept of the
wave -current shear velocity is extended to the case of wave -wave interaction.
Its friction factor is d educed and its effect is significantly changed which
is greater than a simple combination by a factor of 1. 26 incase of a standing
wave . |
| Year | 1987 |
| Corresponding Series Added Entry | Asian Institute of Technology. Dissertation ; no. WA-86-04 |
| Type | Dissertation |
| School | School of Engineering and Technology |
| Department | Other Field of Studies (No Department) |
| Academic Program/FoS | Water Resources Research Engineering (WA) |
| Chairperson(s) | Suphat Vongvisessomjai; |
| Examination Committee(s) | Horikawa, Kiyoshi ;Tawatchai Tingsanchali ;Gupta, Ashim Das ;Huynh, Ngoc Phien ; |
| Scholarship Donor(s) | The Government of Japan ; |
| Degree | Thesis (Ph.D.) - Asian Institute of Technology, 1987 |