scholarly journals Investigation of Nonlinear Wave–Ice Interaction Using Parameter Study and Numerical Simulation

2020 ◽  
Vol 142 (2) ◽  
Author(s):  
Moritz C. N. Hartmann ◽  
Franz von Bock und Polach ◽  
Sören Ehlers ◽  
Norbert Hoffmann ◽  
Miguel Onorato ◽  
...  
Keyword(s):  
Numerical Simulations ◽  
Nonlinear Wave ◽  
Nonlinear Waves ◽  
Water Solution ◽  
Direct Numerical Simulations ◽  
Parameter Study ◽  
Wave Focusing ◽  
Level Ice ◽  
The Impact ◽  
Nonlinear Focusing

Abstract This paper investigates the question of the existence of nonlinear wave–ice interaction with the focus on nonlinear wave propagation and dispersion of waves. The scope of this investigation is to provide a better understanding of ice and wave conditions required to observe nonlinear wave effects under level ice. Direct numerical simulations of nonlinear waves in solid ice are performed within the weakly nonlinear Schrödinger equation (NLSE) framework, using the theoretical findings from Liu and Mollo-Christensen’s 1988 paper. Systematic variations of wave and ice parameters address the impact of the mechanical ice properties and ice thickness on traveling waves of certain wave lengths. The impacts of parameter characteristics on nonlinear focusing and wave dynamics, as well as possible constraints regarding physical consistency, are discussed. It is presented that nonlinear focusing in level ice occurs theoretically. Hereby, distinctive areas of validity with respect to nonlinear wave focusing are identified within the parameter study, which strongly depends on the material properties of the level ice. The results obtained in the parameter study are subsequently used to investigate wave focusing under level ice. Therefore, an exact solution of the NLSE, the Peregrine breather, is utilized. The analytical solution for level ice is compared to the open water solution and accompanied by direct numerical simulations. These investigations show that nonlinear wave focusing can be predicted under level ice for certain parameters. In addition, the agreement of the direct simulations and the analytic solution verifies the numerical approach for nonlinear waves in solid ice.

Numerical Study on Nonlinear Wave-Ice-Interaction

2019 ◽  
Author(s):  
Moritz Hartmann ◽  
R. U. Franz von Bock und Polach ◽  
Sören Ehlers ◽  
Norbert Hoffmann ◽  
Miguel Onorato ◽  
...  
Keyword(s):  
Wave Propagation ◽  
Nonlinear Wave ◽  
Numerical Study ◽  
Wave Interaction ◽  
Parameter Study ◽  
Wave Group ◽  
Nonlinear Wave Propagation ◽  
Level Ice ◽  
Definition Of ◽  
The Impact

Abstract This paper investigates the fundamental question of nonlinear wave-ice interaction under level ice focusing on nonlinear wave propagation and dispersion of waves. Therefore, numerical investigations are performed to verify theoretically if nonlinearity takes place under level ice and if this can lead to intense wave events far away from the ice edge in order to provide an explanation for observed real-world ice break-ups. Therefore, nonlinear wave-ice interaction as well as the impact of the ice characteristics on this interaction will be investigated. The direct numerical simulations of the nonlinear wave propagation under solid ice are performed within the Nonlinear Schrödinger Equation (NLSE) framework. The Peregrine breather solution is applied to represent exact solutions of the NLSE for a nonlinear wave group. The application of such a nonlinear wave group is predestined for the verification of occurring nonlinear wave-wave interaction below the ice sheet. For the definition of wave and ice parameters in the simulation setup, the results of the presented parameter study are used. The parameters are analyzed regarding relevant characteristics of nonlinear wave-ice interaction and wave propagation. By assuming constraints with respect to physical consistency, the parameter range for the NLSE simulations can be narrowed. The scope of this investigation is to provide a better understanding of the ice conditions required to observe nonlinear wave effects under level ice.

scholarly journals Direct Numerical Simulations of the Impact of High Turbulence Intensities and Volume Viscosity on Premixed Methane Flames

2011 ◽  
Vol 2011 ◽  
pp. 1-12 ◽  
Author(s):  
Gordon Fru ◽  
Gábor Janiga ◽  
Dominique Thévenin
Keyword(s):  
Numerical Simulations ◽  
Heat Release ◽  
Turbulent Flame ◽  
Flame Structure ◽  
Turbulent Flames ◽  
Direct Numerical Simulations ◽  
Turbulent Reynolds Number ◽  
Volume Viscosity ◽  
Flame Structures ◽  
The Impact

Parametric direct numerical simulations (DNS) of turbulent premixed flames burning methane in the thin reaction zone regime have been performed relying on complex physicochemical models and taking into account volume viscosity (κ). The combined effect of increasing turbulence intensities (u′) andκon the resulting flame structure is investigated. The turbulent flame structure is marred with numerous perforations and edge flame structures appearing within the burnt gas mixture at various locations, shapes and sizes. Stepping upu′from 3 to 12 m/s leads to an increase in the scaled integrated heat release rate from 2 to 16. This illustrates the interest of combustion in a highly turbulent medium in order to obtain high volumetric heat release rates in compact burners. Flame thickening is observed to be predominant at high turbulent Reynolds number. Via ensemble averaging, it is shown that both laminar and turbulent flame structures are not modified byκ. These findings are in opposition to previous observations for flames burning hydrogen, where significant modifications induced byκwere found for both the local and global properties of turbulent flames. Therefore, to save computational resources, we suggest that the volume viscosity transport term be ignored for turbulent combustion DNS at low Mach numbers when burning hydrocarbon fuels.

scholarly journals An Effect of Electrokinetics Phenomena on Nonlinear Wave Propagation in Bubbly Liquids

2021 ◽  
Vol 26 (3) ◽  
pp. 177-186
Author(s):  
G. Panahov ◽  
E. Abbasov ◽  
S. Bakhtiyarov ◽  
P. Museibli
Keyword(s):  
Wave Propagation ◽  
Fluid Mechanics ◽  
Numerical Simulations ◽  
Nonlinear Wave ◽  
Nonlinear Waves ◽  
Electrical Potential ◽  
Gas Production ◽  
Bubbly Liquid ◽  
Internal Electric Field ◽  
Nonlinear Wave Propagation

Abstract A study of nonlinear waves in liquid-gas mixtures with the consideration of internal effects is an important problem of both the fundamental and the applied fluid mechanics. Investigation of nonlinear waves in the gas-liquid mixtures with allowance for internal effects is an important task of both fundamental and applied fluid mechanics. These problems often arise in industrial processes such as oil and gas production, hydrocarbons pipeline transportation, gas-saturated fluids flow in pipelines, etc. In this work, we investigate the effect of the internal electric field on the nonlinear wave propagation in a bubbly liquid. Numerical simulations have been conducted to study the nonlinear waves described by the nonlinear Burgers-Korteweg-de Vries equation. The numerical simulations showed that the electrokinetic processes significantly affect the wave propagation process. The amplitude of the waves gradually decreases when the size of the gas bubble is decreasing and the electrical potential increases. A good agreement of obtained results with our previous predictions is found.

scholarly journals Numerical Study of the Interaction between Level Ice and Wind Turbine Tower for Estimation of Ice Crushing Loads on Structure

2019 ◽  
Vol 7 (12) ◽  
pp. 439 ◽  
Author(s):  
Ming Song ◽  
Wei Shi ◽  
Zhengru Ren ◽  
Li Zhou
Keyword(s):  
Numerical Simulations ◽  
Wind Turbine ◽  
Numerical Study ◽  
Mesh Size ◽  
Impact Speed ◽  
Wind Turbine Tower ◽  
Comparison Results ◽  
Ice Loads ◽  
Level Ice ◽  
The Impact

In this paper, the interaction between level ice and wind turbine tower is simulated by the explicit nonlinear code LS-DYNA. The isotropic elasto-plastic material model is used for the level ice, in which ice crushing failure is considered. The effects of ice mesh size and ice failure strain on ice forces are investigated. The results indicate that these parameters have a significant effect on the ice crushing loads. To validate and benchmark the numerical simulations, experimental data on level ice-wind turbine tower interactions are used. First, the failure strains of the ice models with different mesh sizes are calibrated using the measured maximum ice force from one test. Next, the calibrated ice models with different mesh sizes are applied for other tests, and the simulated results are compared to corresponding model test data. The effects of the impact speed and the size of wind turbine tower on the comparison between the simulated and measured results are studied. The comparison results show that the numerical simulations can capture the trend of the ice loads with the impact speed and the size of wind turbine tower. When a mesh size of ice model is 1.5 times the ice thickness, the simulations can give more accurate estimations in terms of maximum ice loads for all tests, i.e., good agreement between the simulated and measured results is achieved.

Acceleration statistics of tracer particles in filtered turbulent fields

2018 ◽  
Vol 847 ◽  
Author(s):  
Cristian C. Lalescu ◽  
Michael Wilczek
Keyword(s):  
Particle Size ◽  
Numerical Simulations ◽  
Spatial Scales ◽  
Velocity Fields ◽  
Direct Numerical Simulations ◽  
Small Scale ◽  
Turbulent Fluctuations ◽  
Tracer Particles ◽  
Neutrally Buoyant ◽  
The Impact

We present results from direct numerical simulations of tracer particles advected in filtered velocity fields to quantify the impact of the scales of turbulence on Lagrangian acceleration statistics. Systematically removing spatial scales reduces the frequency of extreme acceleration events, consistent with the notion that they are rooted in the small-scale structure of turbulence. We also find that acceleration variance and flatness as a function of filter scale closely resemble experimental results of neutrally buoyant, finite-sized particles, corroborating the picture that particle size determines the scale on which turbulent fluctuations are sampled.

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