CFD Calculations of Wave-in-Deck Load on a Jacket Platform: Impact Pressure Decrease due to Air Pocket Formation

The industrial problem of a jacket platform subjected to Wave-In-Deck load due to an extreme wave is studied numerically by a CFD technique. In particular, details of local flow and slamming-like hydrodynamic impact on structural members are studied. The applied CFD code ComFLOW is a Navier-Stokes equation solver with an improved Volume of Fluid (iVOF) method employed to displace and re-construct fluids free surface. Two different fluid models, single-phase (liquid+void) and two-phase (liquid+compressible gas) can be used, the latter model being capable of simulating gas entrapped in liquid. Local air pockets are formed in corners and nooks of the structure as the incoming wave front approaches. The study presents a comparison of hydrodynamic impact pressures found with and without the air entrapment. Numerical realisation of the two-phase model is considerably more expensive computationally and the study shows possibility and various aspects of its simulation. Accuracy of the numerical solution and relevance of the air pocket formation on the impact pressures and therefore on the exerted structural load are discussed.

Filter-Based Unsteady RANS Computations for Single-Phase and Cavitating Flows

Volume 3 ◽

10.1115/ht-fed2004-56181 ◽

2004 ◽

Cited By ~ 3

Author(s):

Jiongyang Wu ◽

Wei Shyy ◽

Stein T. Johansen

Keyword(s):

Eddy Viscosity ◽

Single Phase ◽

Experimental Information ◽

Time Dependent ◽

Navier Stokes ◽

Cavitating Flows ◽

Two Phase ◽

Navier Stokes Equation ◽

Filter Size ◽

The widely used Reynolds-Averaged Navier-Stokes (RANS) approach, such as the k-ε two-equation model, has been found to over-predict the eddy viscosity and can dampen out the time dependent fluid dynamics in both single- and two-phase flows. To improve the predictive capability of this type of engineering turbulence closures, a consistent method is offered to bridge the gap between DNS, LES and RANS models. Based on the filter size, conditional averaging is adopted for the Navier-Stokes equation to introduce one more parameter into the definition of the eddy viscosity. Both time-dependent single-phase and cavitating flows are simulated by a pressure-based method and finite volume approach in the framework of the Favre-averaged equations coupled with the new turbulence model. The impact of the filter-based concept, including the filter size and grid dependencies, is investigated using the standard k-ε model and with the available experimental information.

Effects of water–air mixtures on hydraulic transients

Canadian Journal of Civil Engineering ◽

10.1139/l10-066 ◽

2010 ◽

Vol 37 (9) ◽

pp. 1189-1200 ◽

Cited By ~ 5

Author(s):

Oscar Pozos ◽

Alejandro Sanchez ◽

Eduardo A. Rodal ◽

Yuri V. Fairuzov

Keyword(s):

Bubbly Flow ◽

Experimental Investigations ◽

Hydraulic Transients ◽

Two Phase ◽

Pressure Transients ◽

Air Content ◽

Air Pocket ◽

Pressurized Pipelines ◽

Air Pockets ◽

The purpose of this study is to investigate pressurized pipelines and the potential effects on pressure transients of air entrained at the downstream end of large entrapped air pockets followed by a hydraulic jump in pressurized pipelines. The homogeneous two-phase flow model is used to simulate the transient response of the bubbly mixture after a pump shutdown. The results show that pressure transients are significantly reduced with increasing air-pocket volumes and bubbly flow air content. Experimental investigations were carried out to analyze the impact of different air-pocket volumes located at high points of pressurized pipelines. A case study of an existing pumping system was considered to exemplify the impact of the bubbly flow air content on hydraulic transients.

ASME 2016 14th International Conference on Nanochannels, Microchannels, and Minichannels ◽

A Two-Phase Model for Analysis of Blood Flow and Rheological Properties in the Elastic Microvessel

10.1115/icnmm2016-8103 ◽

2016 ◽

Author(s):

Xiaohui Lin ◽

Chibin Zhang ◽

Changbao Wang ◽

Wenquan Chu ◽

Zhaomin Wang

Keyword(s):

Two Phase Flow ◽

Volume Fraction ◽

Transport Model ◽

Planck Equation ◽

Navier Stokes ◽

Phase Flow ◽

Two Phase ◽

Navier Stokes Equation ◽

Experimental Values ◽

The blood in microvascular is seemed as a two-phase flow system composed of plasma and red blood cells (RBCs). Based on hydrodynamic continuity equation, Navier-Stokes equation, Fokker-Planck equation, generalized Reynolds equation and elasticity equation, a two-phase flow transport model of blood in elastic microvascular is proposed. The continuous medium assumption of RBCs is abandoned. The impact of the elastic deformation of the vessel wall, the interaction effect between RBCs, the Brownian motion effect of RBCs and the viscous resistance effect between RBCs and plasma on blood transport are considered. Model does not introduce any phenolmeno-logical parameter, compared with the previous phenolmeno-logical model, this model is more comprehensive in theory. The results show that, the plasma velocity distribution is cork-shaped, which is apparently different with the parabolic shape of the single-phase flow model. The reason of taper angle phenomenon and RBCs “Center focus” phenomenon are also analyzed. When the blood vessel radius is in the order of microns, blood apparent viscosity’s Fahraeus-Lindqvist effect and inverse Fahraeus-Lindqvist effect will occur, the maximum of wall shear stress will appear in the minimum of diameter, the variations of blood apparent viscosity with consider of RBCs volume fraction and shear rate calculated by the model are in good agreement with the experimental values.

Wave-In-Deck Load on a Jacket Platform, CFD-Derived Pressures and Non-Linear Structural Response

Volume 1: Offshore Technology ◽

10.1115/omae2009-79053 ◽

2009 ◽

Cited By ~ 1

Author(s):

Bogdan Iwanowski ◽

Rune Gladso̸ ◽

Marc Lefranc

Keyword(s):

Free Surface ◽

Structural Response ◽

Computational Grids ◽

Navier Stokes ◽

Dynamical Response ◽

Navier Stokes Equation ◽

Local Flow ◽

Jacket Platform ◽

Shell Elements ◽

Non Linear

The paper presents an industrial application of CFD and non-linear structural response codes in offshore technology. A Wave-In-Deck load due to an extreme wave, acting on a jacket platform, is studied numerically. Particular attention is given to details of local flow and local non-linear dynamical response of the structure. A very detailed FEM model of the platform deck structure, composed of shell elements, is embedded into a non body-conforming CFD grid of computational cells. The applied CFD code is a Navier-Stokes equation solver with an improved Volume of Fluid (iVOF) method employed to displace and re-construct fluid’s free surface and uses a simple, Cartesian grid. The two computational grids, FEM and CFD, are independent. The challenge of a direct mapping of CFD-derived fluid pressures onto structural FEM shell elements is addressed. Then the non-linear dynamical response of the structure is found in time domain. The employed CFD code is ComFLOW while the FEM part is handled by the well-known commercial program LS-DYNA. The composed approach utilizes both robustness of VOF-based methods in tracking of the fluid’s free surface and reliability of FEM structural codes such as LS-DYNA.

Review for "A review of drag reduction by additives in curved pipes for single‐phase liquid and two‐phase flows"

10.1002/eng2.12294/v1/review1 ◽

2020 ◽

Author(s):

Alexander Malkin

Keyword(s):

Drag Reduction ◽

Single Phase ◽

Two Phase Flows ◽

Two Phase ◽

Curved Pipes ◽

Review for "A review of drag reduction by additives in curved pipes for single‐phase liquid and two‐phase flows"

10.1002/eng2.12294/v2/review1 ◽

2020 ◽

Keyword(s):

Drag Reduction ◽

Single Phase ◽

Two Phase Flows ◽

Two Phase ◽

Curved Pipes ◽

Review for "A review of drag reduction by additives in curved pipes for single‐phase liquid and two‐phase flows"

10.1002/eng2.12294/v1/review6 ◽

2020 ◽

Author(s):

Ning Yang

Keyword(s):

Drag Reduction ◽

Single Phase ◽

Two Phase Flows ◽

Two Phase ◽

Curved Pipes ◽

CORRELATION OF CONVECTIVE HEAT TRANSFER COEFFICIENT FOR TWO-PHASE LIQUID-VAPOUR FLOW

10.1615/ihtc4.590 ◽

1970 ◽

Cited By ~ 3

Author(s):

J. M. Chawla

Keyword(s):

Heat Transfer ◽

Heat Transfer Coefficient ◽

Transfer Coefficient ◽

Convective Heat Transfer ◽

Convective Heat ◽

Convective Heat Transfer Coefficient ◽

Two Phase ◽

Phase Inversion in Two-Phase Liquid Systems

Collection of Czechoslovak Chemical Communications ◽

10.1135/cccc19921419 ◽

1992 ◽

Vol 57 (7) ◽

pp. 1419-1423

Author(s):

Jindřich Weiss

Keyword(s):

Interfacial Tension ◽

Phase Inversion ◽

Continuous Phase ◽

Considerable Effect ◽

Weak Dependence ◽

Dispersed Phase ◽

Two Phase ◽

Liquid Systems ◽

New data on critical holdups of dispersed phase were measured at which the phase inversion took place. The systems studied differed in the ratio of phase viscosities and interfacial tension. A weak dependence was found of critical holdups on the impeller revolutions and on the material contactor; on the contrary, a considerable effect of viscosity was found out as far as the viscosity of continuous phase exceeded that of dispersed phase.