Serdar Beji | Istanbul Technical University (original) (raw)
Papers by Serdar Beji
Advances in Pure Mathematics
Advances in Pure Mathematics
Coastal Engineering Journal
Advances in Pure Mathematics
Coastal Engineering Journal
International Journal of Environment and Geoinformatics
Coastal Engineering Journal
Coastal Engineering Proceedings
This study investigates fatalities due to rip currents on the Black Sea coast of Istanbul. Result... more This study investigates fatalities due to rip currents on the Black Sea coast of Istanbul. Results include the incidence rate of fatalities from rip currents, their causes, temporal and spatial distributions. The data shows that, nearly 70% of all drowning fatalities are associated with rip currents, and that on the average 33 people reportedly die from rip currents each year in Istanbul Black Sea coast. Thus, considering the wind speeds versus rip current fatalities, about one third of the fatalities occur when the wind speed is between 1.5-2.0 m/s. For the wind speeds 1.0-1.5 m/s the rip current magnitude is not too intense so people consider themselves capable enough to swim but for poor swimmers this is the most dangerous case. Nearly 60% of the fatalities in this wind speed interval is found to be children.
Coastal Engineering Proceedings
A Korteweg & de Vries type equation with improved dispersion characteristics for uneven water dep... more A Korteweg & de Vries type equation with improved dispersion characteristics for uneven water depths is presented. The new KdV type equation contains mixed dispersion and shoaling terms, which extend its applicable range of relative depths to virtually deep waters. The wave equation also satisfies an important consistency condition that there is an exact agreement between the shoaling rate of the equation itself and the rate obtained from the constancy of energy flux. A finite-difference scheme is devised for simulating several linear and nonlinear cases over varying bathymetry. The performance the new KdV type equation is observed to be quite satisfactory.
Coastal Engineering Proceedings
For realistic wave simulations in the nearshore zone besides nonlinear interactions, the dissipat... more For realistic wave simulations in the nearshore zone besides nonlinear interactions, the dissipative effects of wave breaking must also be taken into account. This paper presents the applications of a spectral nonlinear wave model with a dissipative breaking mechanism introduced by Beji and Nadaoka (1997). Results obtained for spectral components are converted to the time series and compared with Beji and Battjes' (1993) laboratory measurements and the field measurements of Nakamura and Katoh (1992) in the surf zone. While the model predicts the spilling-type breaking of irregular waves in acceptable agreement with the measurements in time domain, the agreement is unsatisfactory for plunging-type breakers.
In this work an improved Boussinesq model with a surface pressure term is discretized by a new ap... more In this work an improved Boussinesq model with a surface pressure term is discretized by a new approach. By specifying a single parameter the proposed discretization enables the user to run the program either in the long wave mode without dispersion terms or in the Boussinesq mode. Furthermore, the Boussinesq mode may be run either in the classical Boussinesq mode or in the improved Boussinesq mode by setting the dispersion parameter appropriately. In any one of these modes it is possible to specify a fixed or a moving surface pressure for simulating a moving object on the surface. The numerical model developed here is first tested by comparing the numerically simulated solitary waves with their analytical counterparts. The second test case concerns the comparison of the numerical solutions of moving surface pressures with the analytical solutions of the long wave equations for all possible modes (long wave, classical, and improved Boussinesq).
Http Dx Doi Org 10 1080 0020739920230201, Jul 9, 2006
ABSTRACT Several investigations on cubic polynomials are presented. The studies reported here dea... more ABSTRACT Several investigations on cubic polynomials are presented. The studies reported here deal with certain relationships which hold between the roots of the general cubic equation and other appropriate parameters derived from the same polynomial. Each section is organized in a monotonic sequence; that is, statement, demonstration and verification.
Mediterranean Journal of Mathematics, 2008
International Journal of Mathematical Education in Science and Technology, 1992
ABSTRACT Several investigations on cubic polynomials are presented. The studies reported here dea... more ABSTRACT Several investigations on cubic polynomials are presented. The studies reported here deal with certain relationships which hold between the roots of the general cubic equation and other appropriate parameters derived from the same polynomial. Each section is organized in a monotonic sequence; that is, statement, demonstration and verification.
Coastal Engineering, 1995
ABSTRACT A nonlinearity parameter which is valid for both deep and shallow water waves is introdu... more ABSTRACT A nonlinearity parameter which is valid for both deep and shallow water waves is introduced. The parameter may be regarded as a wave Froude number. A modified form of the Ursell number is also discussed.
Coastal Engineering, 1998
Coastal Engineering, 2013
Advances in Pure Mathematics
Advances in Pure Mathematics
Coastal Engineering Journal
Advances in Pure Mathematics
Coastal Engineering Journal
International Journal of Environment and Geoinformatics
Coastal Engineering Journal
Coastal Engineering Proceedings
This study investigates fatalities due to rip currents on the Black Sea coast of Istanbul. Result... more This study investigates fatalities due to rip currents on the Black Sea coast of Istanbul. Results include the incidence rate of fatalities from rip currents, their causes, temporal and spatial distributions. The data shows that, nearly 70% of all drowning fatalities are associated with rip currents, and that on the average 33 people reportedly die from rip currents each year in Istanbul Black Sea coast. Thus, considering the wind speeds versus rip current fatalities, about one third of the fatalities occur when the wind speed is between 1.5-2.0 m/s. For the wind speeds 1.0-1.5 m/s the rip current magnitude is not too intense so people consider themselves capable enough to swim but for poor swimmers this is the most dangerous case. Nearly 60% of the fatalities in this wind speed interval is found to be children.
Coastal Engineering Proceedings
A Korteweg & de Vries type equation with improved dispersion characteristics for uneven water dep... more A Korteweg & de Vries type equation with improved dispersion characteristics for uneven water depths is presented. The new KdV type equation contains mixed dispersion and shoaling terms, which extend its applicable range of relative depths to virtually deep waters. The wave equation also satisfies an important consistency condition that there is an exact agreement between the shoaling rate of the equation itself and the rate obtained from the constancy of energy flux. A finite-difference scheme is devised for simulating several linear and nonlinear cases over varying bathymetry. The performance the new KdV type equation is observed to be quite satisfactory.
Coastal Engineering Proceedings
For realistic wave simulations in the nearshore zone besides nonlinear interactions, the dissipat... more For realistic wave simulations in the nearshore zone besides nonlinear interactions, the dissipative effects of wave breaking must also be taken into account. This paper presents the applications of a spectral nonlinear wave model with a dissipative breaking mechanism introduced by Beji and Nadaoka (1997). Results obtained for spectral components are converted to the time series and compared with Beji and Battjes' (1993) laboratory measurements and the field measurements of Nakamura and Katoh (1992) in the surf zone. While the model predicts the spilling-type breaking of irregular waves in acceptable agreement with the measurements in time domain, the agreement is unsatisfactory for plunging-type breakers.
In this work an improved Boussinesq model with a surface pressure term is discretized by a new ap... more In this work an improved Boussinesq model with a surface pressure term is discretized by a new approach. By specifying a single parameter the proposed discretization enables the user to run the program either in the long wave mode without dispersion terms or in the Boussinesq mode. Furthermore, the Boussinesq mode may be run either in the classical Boussinesq mode or in the improved Boussinesq mode by setting the dispersion parameter appropriately. In any one of these modes it is possible to specify a fixed or a moving surface pressure for simulating a moving object on the surface. The numerical model developed here is first tested by comparing the numerically simulated solitary waves with their analytical counterparts. The second test case concerns the comparison of the numerical solutions of moving surface pressures with the analytical solutions of the long wave equations for all possible modes (long wave, classical, and improved Boussinesq).
Http Dx Doi Org 10 1080 0020739920230201, Jul 9, 2006
ABSTRACT Several investigations on cubic polynomials are presented. The studies reported here dea... more ABSTRACT Several investigations on cubic polynomials are presented. The studies reported here deal with certain relationships which hold between the roots of the general cubic equation and other appropriate parameters derived from the same polynomial. Each section is organized in a monotonic sequence; that is, statement, demonstration and verification.
Mediterranean Journal of Mathematics, 2008
International Journal of Mathematical Education in Science and Technology, 1992
ABSTRACT Several investigations on cubic polynomials are presented. The studies reported here dea... more ABSTRACT Several investigations on cubic polynomials are presented. The studies reported here deal with certain relationships which hold between the roots of the general cubic equation and other appropriate parameters derived from the same polynomial. Each section is organized in a monotonic sequence; that is, statement, demonstration and verification.
Coastal Engineering, 1995
ABSTRACT A nonlinearity parameter which is valid for both deep and shallow water waves is introdu... more ABSTRACT A nonlinearity parameter which is valid for both deep and shallow water waves is introduced. The parameter may be regarded as a wave Froude number. A modified form of the Ursell number is also discussed.
Coastal Engineering, 1998
Coastal Engineering, 2013