scholarly journals A Study on the Dynamic Ground Effect on Three-Dimensional Wings Using a Time Domain Panel Method

2002 ◽  
Vol 30 (4) ◽  
pp. 10-17
Keyword(s):  
Time Domain ◽  
Three Dimensional ◽  
Ground Effect ◽  
Panel Method

Ship Seakeeping Through the t = 1/4 Critical Frequency

1998 ◽  
Vol 42 (02) ◽  
pp. 113-119
Author(s):  
D. C. Kring
Keyword(s):  
Numerical Analysis ◽  
Time Domain ◽  
Critical Frequency ◽  
Three Dimensional ◽  
Panel Method ◽  
Gravitational Acceleration ◽  
Forward Speed ◽  
Rankine Panel Method ◽  
Physical Experiments

This study demonstrates that a bounded, physically relevant solution does exist at the so-called T = Uω/g = 1/4 resonance in the linear seakeeping problem for a realistic ship with forward speed, U, frequency of encounter, ω, and gravitational acceleration, g. The solution of the seakeeping problem by a linear, three dimensional, time-domain Rankine panel method, validated through numerical analysis, testing, and comparison to physical experiments, supports this claim. The solution can also be obtained with equal validity through frequencies both above and below the critical frequency.

Motion Prediction of the Ship With Sloshing Tanks

2009 ◽  
Author(s):  
Kang Zou ◽  
Quan-ming Miao ◽  
Ren-qing Zhu
Keyword(s):  
Time Domain ◽  
Three Dimensional ◽  
Panel Method ◽  
Ship Motion ◽  
Motion Prediction ◽  
Ship Motions ◽  
Motion Responses ◽  
Motion Problem ◽  
Good Agreement

Sloshing flow in ship tanks is excited by ship motions, but it affects the ship motions in reverse. This paper focuses on the motion responses of the ship in waves with consideration of coupled effects with sloshing in tanks. A three-dimensional panel method in time-domain is applied to solve the ship motion problem, and the sloshing tanks are solved by commercial CFD software simultaneously. Experiments were carried out on a SL175 ship and good agreement is obtained.

scholarly journals On Unsteady Effects in WIG Craft Aerodynamics

2019 ◽  
Vol 2019 ◽  
pp. 1-14 ◽  
Author(s):  
Nikolai Kornev
Keyword(s):  
Time Domain ◽  
Potential Flow ◽  
Three Dimensional ◽  
Ground Effect ◽  
Two Dimensional ◽  
Unsteady Forces ◽  
Longitudinal Plane ◽  
Ground Effects ◽  
Unsteady Effects

The paper presents the analysis of unsteady forces and their influence on the aerodynamics and motion of a wing-in-ground (WIG) effect craft. Two-dimensional and three-dimensional aerodynamic models based on the potential flow are coupled with time domain simulations in the longitudinal plane. A special attention is paid to the explanation of the dynamic ground effect on both the sink and pitching motions. The influence of unsteady and quasi-steady forces on the dynamic ground effects and the craft motion is analyzed for different heights of flight.

scholarly journals Hydrodynamic Analysis and Motions of Ship with Forward Speed via a Three-Dimensional Time-Domain Panel Method

2021 ◽  
Vol 9 (1) ◽  
pp. 87
Author(s):  
Peng Zhang ◽  
Teng Zhang ◽  
Xin Wang
Keyword(s):  
Time Domain ◽  
Three Dimensional ◽  
Impulse Response Function ◽  
Panel Method ◽  
Linear Potential ◽  
Forward Speed ◽  
Precise Integration ◽  
Response Function Method ◽  
Surface Green Function ◽  
Linear Potential Theory

A new three-dimensional (3D) time-domain panel method is developed to solve the ship hydrodynamic problem and motions. For an advancing ship with a constant forward speed in regular waves, the ship’s hull can be discretized and processed into a number of quadrilateral panels. Based on Green’s theorem, an analytical expression for Froude–Krylov (F–K) forces evaluation on the quadrilateral panels is derived without accuracy loss. Within the linear potential theory, the transient free surface Green function (TFSGF) is applied to solve the boundary value problem. To improve the efficiency and numerical stability of TFSGF evaluation, a precise integration method with variable parameters setting for extended identity matrix is developed to compute the TFSGF in the computation domain. Then, radiation and diffraction forces can be evaluated by means of the impulse response function method. The Wigley I hull form is taken as a study case, and the computed hydrodynamic coefficients, wave exciting forces, and motions by the present method are compared with previous literature experimental data and prior published results. It manifests that the three-dimensional time-domain panel method proposed in this paper has good accuracy.

Prediction of Ship Motions Via a Three-Dimensional Time-Domain Method Following a Quad-Tree Adaptive Mesh Technique

2020 ◽  
Vol 27 (1) ◽  
pp. 29-38
Author(s):  
Teng Zhang ◽  
Junsheng Ren ◽  
Lu Liu
Keyword(s):  
Free Surface ◽  
Incident Wave ◽  
Time Domain ◽  
Three Dimensional ◽  
Adaptive Mesh ◽  
Wave Profile ◽  
Time Domain Method ◽  
Ship Motions ◽  
Quad Tree ◽  
Mesh Technique

AbstractA three-dimensional (3D) time-domain method is developed to predict ship motions in waves. To evaluate the Froude-Krylov (F-K) forces and hydrostatic forces under the instantaneous incident wave profile, an adaptive mesh technique based on a quad-tree subdivision is adopted to generate instantaneous wet meshes for ship. For quadrilateral panels under both mean free surface and instantaneous incident wave profiles, Froude-Krylov forces and hydrostatic forces are computed by analytical exact pressure integration expressions, allowing for considerably coarse meshes without loss of accuracy. And for quadrilateral panels interacting with the wave profile, F-K and hydrostatic forces are evaluated following a quad-tree subdivision. The transient free surface Green function (TFSGF) is essential to evaluate radiation and diffraction forces based on linear theory. To reduce the numerical error due to unclear partition, a precise integration method is applied to solve the TFSGF in the partition computation time domain. Computations are carried out for a Wigley hull form and S175 container ship, and the results show good agreement with both experimental results and published results.

scholarly journals The time domain numerical method of three-dimensional conductors including radiation with lumped parameter circuit

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Souma Jinno ◽  
Shuji Kitora ◽  
Hiroshi Toki ◽  
Masayuki Abe
Keyword(s):  
Numerical Method ◽  
Time Domain ◽  
Maxwell Equations ◽  
Three Dimensional ◽  
New Formalism ◽  
Vector Potentials ◽  
Lumped Parameter ◽  
Radiation Theory ◽  
Stable Solutions ◽  
The Time Domain

AbstractWe formulate a numerical method on the transmission and radiation theory of three-dimensional conductors starting from the Maxwell equations in the time domain. We include the delay effect in the integral equations for the scalar and vector potentials rigorously, which is vital to obtain numerically stable solutions for transmission and radiation phenomena in conductors. We provide a formalism to connect the conductors to any passive lumped-parameter circuits. We show one example of numerical calculations, demonstrating that the new formalism provides stable solutions to the transmission and radiation phenomena.

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