scholarly journals INTERACTION BETWEEN WAVES AND HANGING HIGHLY FLEXIBLE KELP BLADES

2018 ◽  
pp. 31 ◽  
Author(s):  
Long-Huan Zhu ◽  
Kimberly Huguenard ◽  
David Fredriksson
Keyword(s):  
Sediment Transport ◽  
Numerical Model ◽  
Immersed Boundary Method ◽  
Aquatic Vegetation ◽  
Wave Model ◽  
Immersed Boundary ◽  
Cable Model ◽  
Nutrient Distribution ◽  
Boundary Method ◽  
Recent Attention

The interaction between waves and flexible blades has drawn recent attention because of the capacity of nature-based infrastructure, such as aquatic vegetation and kelp, to attenuate waves. In this study, a new numerical model was developed to study the wave-blade interaction for both bottom-fixed and suspended blades. The dynamics of the blades simulated by a cable model were coupled with OpenFOAM®-based wave model IHFoam with the immersed boundary method. The results showed that the distribution of the blade-induced vortices was asymmetric with more vortices upstream for the single bottom-fixed blade while more vortices downstream for the single suspended blade. For both submerged and suspended canopies, the vortex distribution is also asymmetric. More vortices concentrate upstream for the submerged canopy. For a suspended canopy, more vortices concentrate upstream and below the bottom of the suspended canopy. Yet near the surface above the suspended canopy, more vortices concentrate downstream. Understanding the distribution of vortices is important for predicting the sediment transport and nutrient distribution.

Numerical simulation of h-adaptive immersed boundary method for freely falling disks

2018 ◽  
Vol 32 (12n13) ◽  
pp. 1840002
Author(s):  
Pan Zhang ◽  
Zhenhua Xia ◽  
Qingdong Cai
Keyword(s):  
Numerical Simulation ◽  
Numerical Model ◽  
Aspect Ratio ◽  
Immersed Boundary Method ◽  
Adaptive Mesh Refinement ◽  
Degrees Of Freedom ◽  
Adaptive Mesh ◽  
Immersed Boundary ◽  
Six Degrees Of Freedom ◽  
Boundary Method

In this work, a freely falling disk with aspect ratio 1/10 is directly simulated by using an adaptive numerical model implemented on a parallel computation framework JASMIN. The adaptive numerical model is a combination of the h-adaptive mesh refinement technique and the implicit immersed boundary method (IBM). Our numerical results agree well with the experimental results in all of the six degrees of freedom of the disk. Furthermore, very similar vortex structures observed in the experiment were also obtained.

Coupled Simulation of Oscillatory Flow, Sediment Transport and Morphology Evolution of Ripples Based on the Immersed Boundary Method

2014 ◽  
Author(s):  
Georgios A. Leftheriotis ◽  
Athanassios A. Dimas
Keyword(s):  
Sediment Transport ◽  
Numerical Solution ◽  
Suspended Sediment ◽  
Immersed Boundary Method ◽  
Oscillatory Flow ◽  
Orbital Motion ◽  
Immersed Boundary ◽  
Morphology Evolution ◽  
Boundary Method ◽  
Motion Amplitude

In the present study, numerical simulations of oscillatory flow over a rippled bottom, coupled with bed and suspended sediment transport, as well as the resulting morphology evolution, are performed. The simulations are based on the numerical solution of the Navier-Stokes equations and the advection-diffusion equation for the suspended load, while empirical formulas are used for the bed load. The bed morphological evolution is obtained by the numerical solution of the conservation of sediment mass equation. A fractional time-step scheme is used for the temporal discretization, while finite differences are used for the spatial discretization on a Cartesian grid. The Immersed Boundary method is implemented for the imposition of fluid and sediment boundary conditions on the ripple surface. Two types of ripples are examined, i.e., ripples of parabolic shape with sharp crests and sinusoidal ripples, and cases of ripple length to orbital motion amplitude ratio of 1.6 and ripple height to orbital motion amplitude ratios of 0.16, 0.20 and 0.24, at Reynolds number equal to 5×103. The effect of ripple steepness and ripple shape on suspended sediment and ripple migration is discussed.

Numerical Simulation of Wave Propagation Over Submerged Composite Breakwaters Using the Immersed Boundary Method

2014 ◽  
Author(s):  
Theofano I. Koutrouveli ◽  
Athanassios A. Dimas
Keyword(s):  
Free Surface ◽  
Numerical Model ◽  
Immersed Boundary Method ◽  
Stokes Equations ◽  
Splitting Method ◽  
Staggered Grid ◽  
Immersed Boundary ◽  
Two Phase ◽  
Boundary Method ◽  
Two Dimensional Flow

The two-dimensional flow induced by waves over submerged breakwaters of two different shapes is studied by means of a two-phase (water and air) Navier-Stokes equations solver. A time-splitting method is used for the temporal discretization, while the spatial discretization is based on the use of finite differences in a Cartesian staggered grid. The implementation of the boundary conditions at solid surfaces, as well as the treatment of the free surface is performed using the immersed boundary method where the breakwater, the seabed and the free surface are boundaries immersed in the numerical grid. The numerical model was applied on the propagation and breaking over a constant slope beach, as well as on the propagation and nonlinear transformation of waves over two types of submerged breakwaters, i.e., trapezoidal and composite (with berm in the up-slope side). The results of the numerical model reveal that the presence of the berm reduces the transmission coefficient and this reduction increases with the decrease of the berm depth of submergence.

Sign in / Sign up

Export Citation Format

Share Document