Determination of free surface flow characteristics of free falling fluid over an inclined plate by opto-coupler arrangement

2002 ◽  
Author(s):  
H. Camur ◽  
K. Balasubramanian ◽  
O.E. Peremeci
Keyword(s):  
Free Surface ◽  
Flow Characteristics ◽  
Free Surface Flow ◽  
Surface Flow ◽  
Inclined Plate ◽  
Free Falling

Role of rigid boundary on the decay of turbulence generated by passive-grid for free surface flow

2020 ◽  
pp. 095440622094256 ◽  
Author(s):  
Pankaj Kumar Raushan ◽  
Santosh Kumar Singh ◽  
Koustuv Debnath
Keyword(s):  
Free Surface ◽  
Near Field ◽  
Flow Characteristics ◽  
Joint Probability ◽  
Mesh Size ◽  
Free Surface Flow ◽  
Surface Flow ◽  
Solid Boundary ◽  
Joint Probability Distribution ◽  
Rigid Boundary

The present study aims to investigate the flow characteristics of grid-generated turbulence under the consideration of solid boundary in free surface flow. To understand the nature of isotropy and anisotropy in the flow, the turbulent intensity is evaluated at the downstream of the grid for different mesh sizes. The energy spectrums based on the Fast Fourier and marginal Hilbert–Huang transform are presented to understand the decay of energy in the associated spectral frequency domain. It is observed that the peak of energy associated with the Fourier spectrum decreases in the near-field region of the grid with the increase in mesh size of the grid. Further, to characterise the concentrated velocity fluctuations, the paper strives to analyse the joint probability distribution function and the local intermittency measure in the close and far stream of the grid. The autocorrelation functions and the magnitude of integral length scale of the stream-wise fluctuating velocity components are also presented at two different vertical levels from the solid boundary. The normalised Shannon entropy is also evaluated to characterise the degree of the orderness or disorderness in the flow due to the interaction of grid and rigid boundary.

scholarly journals Determinants of modelling choices for 1-D free-surface flow and morphodynamics in hydrology and hydraulics: a review

2016 ◽  
Vol 20 (9) ◽  
pp. 3799-3830 ◽  
Author(s):  
Bruno Cheviron ◽  
Roger Moussa
Keyword(s):  
Free Surface ◽  
Flow Characteristics ◽  
Free Surface Flow ◽  
Surface Flow ◽  
Navier Stokes ◽  
Dimensionless Time ◽  
Dimensionless Numbers ◽  
Model Refinement ◽  
Modelling Strategies ◽  
Spatiotemporal Scales

Abstract. This review paper investigates the determinants of modelling choices, for numerous applications of 1-D free-surface flow and morphodynamic equations in hydrology and hydraulics, across multiple spatiotemporal scales. We aim to characterize each case study by its signature composed of model refinement (Navier–Stokes: NS; Reynolds-averaged Navier–Stokes: RANS; Saint-Venant: SV; or approximations to Saint-Venant: ASV), spatiotemporal scales and subscales (domain length: L from 1 cm to 1000 km; temporal scale: T from 1 s to 1 year; flow depth: H from 1 mm to 10 m; spatial step for modelling: δL; temporal step: δT), flow typology (Overland: O; High gradient: Hg; Bedforms: B; Fluvial: F), and dimensionless numbers (dimensionless time period T*, Reynolds number Re, Froude number Fr, slope S, inundation ratio Λz, Shields number θ). The determinants of modelling choices are therefore sought in the interplay between flow characteristics and cross-scale and scale-independent views. The influence of spatiotemporal scales on modelling choices is first quantified through the expected correlation between increasing scales and decreasing model refinements (though modelling objectives also show through the chosen spatial and temporal subscales). Then flow typology appears a secondary but important determinant in the choice of model refinement. This finding is confirmed by the discriminating values of several dimensionless numbers, which prove preferential associations between model refinements and flow typologies. This review is intended to help modellers in positioning their choices with respect to the most frequent practices, within a generic, normative procedure possibly enriched by the community for a larger, comprehensive and updated image of modelling strategies.

An Adjoint Formulation for Shape Optimization in Free-Surface Potential Flow

2001 ◽  
Vol 45 (04) ◽  
pp. 269-278
Author(s):  
Saad A. Ragab
Keyword(s):  
Free Surface ◽  
Shape Optimization ◽  
Three Dimensional ◽  
Optimal Solution ◽  
Free Surface Flow ◽  
Surface Flow ◽  
Optimization Techniques ◽  
Marine Vehicles ◽  
Direct Calculations

This paper is a step towards the application of automatic shape optimization techniques to the hydrodynamic design of marine vehicles. The flow is assumed to be irrotational and free-surface conditions are linearized. Several objective functionals of relevance to free-surface flow are proposed, and adjoint formulations for the determination of their gradients are derived. The accuracy of the gradient using the adjoint formulations has been verified by comparisons with direct calculations using second-order finite differences. The method is then used to obtain an optimal solution to the inverse problem for a three-dimensional body submerged near a free surface, and to design a minimum wave resistance body.

scholarly journals Determinants of modelling choices for 1-D free-surface flow and erosion issues in hydrology: a review

2015 ◽  
Vol 12 (9) ◽  
pp. 9091-9155
Author(s):  
B. Cheviron ◽  
R. Moussa
Keyword(s):  
Free Surface ◽  
Flow Characteristics ◽  
Free Surface Flow ◽  
Surface Flow ◽  
Navier Stokes ◽  
Dimensionless Time ◽  
Dimensionless Numbers ◽  
Model Refinement ◽  
Modelling Strategies ◽  
Spatiotemporal Scales

Abstract. This review paper investigates the determinants of modelling choices, for numerous applications of 1-D free-surface flow and erosion equations, across multiple spatiotemporal scales. We aim to characterize each case study by its signature composed of model refinement (Navier-Stokes: NS, Reynolds-Averaged Navier-Stokes: RANS, Saint-Venant: SV or Approximations of Saint-Venant: ASV), spatiotemporal scales (domain length: L from 1 cm to 1000 km; temporal scale: T from 1 second to 1 year; flow depth: H from 1 mm to 10 m), flow typology (Overland: O, High gradient: Hg, Bedforms: B, Fluvial: F) and dimensionless numbers (Dimensionless time period T*, Reynolds number Re, Froude number Fr, Slope S, Inundation ratio Λz, Shields number θ). The determinants of modelling choices are therefore sought in the interplay between flow characteristics, cross-scale and scale-independent views. The influence of spatiotemporal scales on modelling choices is first quantified through the expected correlation between increasing scales and decreasing model refinements, identifying then flow typology a secondary but mattering determinant in the choice of model refinement. This finding is confirmed by the discriminating values of several dimensionless numbers, that prove preferential associations between model refinements and flow typologies. This review is intended to help each modeller positioning his (her) choices with respect to the most frequent practices, within a generic, normative procedure possibly enriched by the community for a larger, comprehensive and updated image of modelling strategies.

scholarly journals Laminar free-surface flow into a vertical cylinder

1975 ◽  
Vol 3 (1) ◽  
pp. 51-68 ◽  
Author(s):  
Thomas G. Smith ◽  
J.O. Wilkes
Keyword(s):  
Free Surface ◽  
Vertical Cylinder ◽  
Free Surface Flow ◽  
Surface Flow

Free-Surface Flow Simulations With Interactively Moving Bodies

2017 ◽  
Author(s):  
Arthur E. P. Veldman ◽  
Henk Seubers ◽  
Peter van der Plas ◽  
Joop Helder
Keyword(s):  
Free Surface ◽  
Free Fall ◽  
Free Surface Flow ◽  
Surface Flow ◽  
Numerical Solution Method ◽  
Flow Simulations ◽  
Floating Object ◽  
Offshore Industry ◽  
Floating Objects ◽  
Moving Bodies

The simulation of free-surface flow around moored or floating objects faces a series of challenges, concerning the flow modelling and the numerical solution method. One of the challenges is the simulation of objects whose dynamics is determined by a two-way interaction with the incoming waves. The ‘traditional’ way of numerically coupling the flow dynamics with the dynamics of a floating object becomes unstable (or requires severe underrelaxation) when the added mass is larger than the mass of the object. To deal with this two-way interaction, a more simultaneous type of numerical coupling is being developed. The paper will focus on this issue. To demonstrate the quasi-simultaneous method, a number of simulation results for engineering applications from the offshore industry will be presented, such as the motion of a moored TLP platform in extreme waves, and a free-fall life boat dropping into wavy water.

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