A 3D Coupled Fluid-Flexible Multibody Solver for Offshore Vessel-Riser System

Joshi, Vaibhav; Gurugubelli, Pardha S.; Law, Yun Zhi; Jaiman, Rajeev K.; Adaikalaraj, Peter Francis Bernad

doi:10.1115/omae2018-78281

Cited by 7 publications

(3 citation statements)

References 0 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…In contrast to the traditional approaches to evolve the fluid-fluid interface of the two-phase flow like volume-of-fluid (VOF) and level-set which require some kind of geometric manipulation which can be computationally expensive in three-dimensions [24], we utilize the diffuse interface description which originate from thermodynamically consistent theories of phase transitions and avoid any kind of geometric manipulations. The diffused interface has a finite thickness (O(ε)) and is evolved by the minimization of the Ginzburg-Landau energy functional,…”

Section: Two-phase Flow Modeling With Moving Boundarymentioning

confidence: 99%

Transverse flow-induced vibrations of a sphere in the proximity of a free surface: A numerical study

Chizfahm,

Joshi,

Jaiman

2020

Preprint

View full text Add to dashboard Cite

In this paper, we present a numerical study on the transverse flow-induced vibration (FIV) of an elastically mounted sphere in the vicinity of a free surface at subcritical Reynolds numbers. We assess the interaction dynamics and the vibration characteristics of fully submerged and piercing spheres that are free to vibrate in the transverse direction. We employ the recently developed three-dimensional two-phase flow-structure interaction solver to investigate fully and partially submerged configurations of an elastically mounted sphere. To begin, we examine the vortex-induced vibration (VIV) phenomenon and the vortex-shedding modes of a fully-submerged sphere vibrating freely in all three spatial directions. We systematically verify and analyze the mode transitions and the motion trajectories in the three degrees-of-freedom (3-DOF) for the Reynolds number up to 30 000. We next simulate the transversely vibrating (1-DOF) full-submerged sphere over a wide range of reduced velocities 3 ≤ U * ≤ 20, whereby the reduced velocity is adjusted by changing the freestream Reynolds number. The VIV response amplitude and the topology of the wake structure are compared with the measurements for the mode I and mode II response branches. We further look into the effect of the free surface on the FIV response of a transversely vibrating sphere in the proximity of a free surface. The response dynamics of the sphere is studied for three representative values of normalized immersion ratio (h * = h/D, where h is the distance from the top of the sphere to undisturbed free-surface level and D is the sphere diameter), at h * = 1 (fully submerged sphere with no free-surface effect), h * = 0 (where the top of the sphere touches the free surface) and h * = −0.25 (where the sphere pierces the free surface). At the lock-in range, we observe that the amplitude response of the sphere at h * = 0 is decreased significantly compared to the case at h * = 1. It is found that the vorticity flux is diffused due to the free-surface boundary and the free surface acts as a sink of energy that leads to a reduction in the transverse force and amplitude response. When the sphere pierces the free surface at h * = −0.25, the amplitude response at the lock-in state is found to be greater than all the submerged cases studied with the maximum peak-to-peak amplitude of ∼ 2D. We find that the interaction of the piercing sphere with the air-water interface causes a relatively large surface deformation and has a significant impact on the synchronization of the vortex shedding and the vibration frequency. The streamwise vorticity contours and pressure distribution are employed to understand the VIV characteristics and wake dynamics. Increased streamwise vorticity gives rise to a relatively larger transverse force to the piercing

show abstract

Section: Two-phase Flow Modeling With Moving Boundarymentioning

confidence: 99%

Transverse flow-induced vibrations of a sphere in the proximity of a free surface: A numerical study

Chizfahm,

Joshi,

Jaiman

2020

Preprint

View full text Add to dashboard Cite

show abstract

“…Fluid-structure interaction (FSI) is a coupled highly-nonlinear multiphysics problem that can be found in various natural phenomena and industrial processes. Examples include from traditional aeroelasticity and flow-induced vibration problems in aerospace engineering [1,2,3,4], marine/offshore [5,6,7,8], biomedical [9,10,11], energy harvesting [12] to the emerging fields of muscular hydrostat [13,14] and soft robotics [15] and bio-inspired flying vehicles [16]. The interface between the fluid and solid poses significant challenges in mathematical modeling and numerical simulation [17,18].…”

Section: Introductionmentioning

confidence: 99%

An interface and geometry preserving phase-field method for fully Eulerian fluid-structure interaction

Mao¹,

Jaiman²

2022

Preprint

View full text Add to dashboard Cite

We present an interface and geometry preserving (IGP) method for the modeling of fully Eulerian fluid-structure interaction via phase-field formulation. While the hyperbolic tangent interface profile is preserved by the time-dependent mobility model, the proposed method maintains the geometry of the solid-fluid interface by reducing the volume-conserved mean curvature flow. To achieve the reduction in the curvature flow, we construct a gradient-minimizing velocity field (GMV) for the convection of the order parameter. The constructed velocity field enables the preservation of the solid velocity in the solid domain while extending the velocity in the normal direction throughout the diffuse interface region. With this treatment, the GMV reduces the normal velocity difference of the level sets of the order parameter which alleviates the undesired thickening or thinning of the diffuse interface region due to the convection. During this process, the time-dependent mobility coefficient is substantially reduced and there is a lesser volume-conserved mean curvature flow. The GMV ensures that the diffuse interface region moves with the solid bulk such that the fluid-solid interface conforms to the geometry of the solid. Using the unified momentum equation and the phase-dependent interpolation, we integrate the IGP method into a fully Eulerian variational FSI solver based on the incompressible viscous fluid and the neo-Hookean solid. We first demonstrate the ability of the phase-field-based IGP method for the convection of circular and square interfaces with a prescribed velocity field. The variational FSI framework with the IGP method is then examined for the flow passing a fixed deformable block in a channel domain. Finally, the vibration of a plate attached behind a stationary cylinder subjected to incoming flow is employed to assess the fully Eulerian framework for a large aspect ratio and sharp corners.

show abstract

“…Fluid-structure interaction (FSI) is a coupled physical phenomenon that involves a mutual interplay and bidirectional interaction of fluid flow with structural dynamics. This phenomenon is ubiquitous in nature and engineering systems such as fluttering flags [51,16], flying bats [10,23], offshore platforms and pipelines [21,22] and ship maneuvering [53]. For example, the two-way coupling between fluid and solid exhibits rich flow dynamics such as wake-body interaction and vortex-induced vibrations (VIVs) [28], which are important to understand from an engineering design or a decision-making standpoint.…”

Section: Introductionmentioning

confidence: 99%

A hybrid partitioned deep learning methodology for moving interface and fluid-structure interaction

Gupta¹,

Jaiman²

2021

Preprint

View full text Add to dashboard Cite

In this work, we present a hybrid physics-based deep learning (DL) framework for handling moving interfaces and predicting fluid-structure interaction (FSI). Using the discretized Navier-Stokes (NS) in the Arbitrary Lagrangian-Eulerian (ALE) reference frame, we generate full-order flow snapshots and point-cloud displacements as target physical data for the learning and inference of coupled fluid-structure dynamics. This integrated operation of the physics-based modeling with the DL-based reduced-order model (DL-ROM) makes our framework hybrid. The proposed multi-level framework is composed of two data-driven physics-DL drivers that predict unsteady flow and track the moving point cloud displacements respectively, while synchronously exchange the force information at the physical interface. The first component of our proposed framework relies on the proper orthogonal decomposition-based recurrent neural network (POD-RNN) as a semi-supervised procedure to infer the point cloud ALE description. This model essentially relies on the POD basis modes to reduce dimensionality and evolving them in the time domain. The second component utilizes the convolution-based recurrent autoencoder network (CRAN) as a self-supervised DL procedure to predict the nonlinear flow dynamics at static Eulerian probes. We introduce these probes as spatially structured query nodes in the moving point cloud to resolve the field Lagrangian to Eulerian conflict as well as conveniently train the CRAN driver. We design a novel snapshot-field transfer and load recovery (FTLR) algorithm to optimally select these Eulerian probes. They are selected in such a way that the two components (i.e., POD-RNN and CRAN) are constrained at the interface to recover bulk force quantities. These hybrid physics-DL drivers ultimately rely on recurrent neural networks to evolve the low-dimensional state. A popular prototypical fluid-structure interaction problem of flow past a freely oscillating cylinder is selected to test the efficacy of the proposed hybrid DL-ROM methodology. The framework tracks the interface description accurately and predicts highly non-linear wake dynamics for nearly 500 time-steps with limited input demonstrator within excellent to a reasonable accuracy. These results motivate us to further explore the application of this hybrid framework for the concept of digital twinning of engineering systems, especially those involving moving boundaries and fluid-structure interactions.

show abstract

A 3D Coupled Fluid-Flexible Multibody Solver for Offshore Vessel-Riser System

Cited by 7 publications

References 0 publications

Transverse flow-induced vibrations of a sphere in the proximity of a free surface: A numerical study

Transverse flow-induced vibrations of a sphere in the proximity of a free surface: A numerical study

An interface and geometry preserving phase-field method for fully Eulerian fluid-structure interaction

A hybrid partitioned deep learning methodology for moving interface and fluid-structure interaction

Contact Info

Product

Resources

About