scholarly journals CFD-FEM Modeling of a Floating Foundation under Extreme Hydrodynamic Forces Generated by Low Sea States

2021 ◽  
Vol 8 (6) ◽  
pp. 888-896
Author(s):  
Juan Gabriel Rueda-Bayona ◽  
Laura Gil ◽  
Jose Manuel Calderón
Keyword(s):  
Numerical Data ◽  
Hydrodynamic Forces ◽  
Current Data ◽  
Floating Structure ◽  
Fem Modeling ◽  
Energy Projects ◽  
Computational Fluid Dynamics Cfd ◽  
Offshore Industry ◽  
Dynamics Problems

The high development of the offshore industry for supporting new marine and renewable energy projects requires a constant improvement of methods for structure designing. Because recent studies warned that maximum environmental loads occur during low sea states and not during extreme sea states as recommend by the offshore standards (e.g., RP 2AWSD-2014), this study used measured wave and current data for analyzing that warning. The Colombian Caribbean coast was selected as the study area, and in situ ADCP data combined with Reanalysis and numerical data was used for identifying proper sea states for the analysis. Then, two low and one extreme sea states were selected and their associated current profiles were extracted, for providing input data for Computational Fluid Dynamics (CFD) and Finite Element Method (FEM) simulations to evaluate the effect of the hydrodynamic forces over a floating structure. The results showed that low sea states generated maximum loads and rotations in the floating structure, and the extreme sea states caused high-frequency vibrations that could provoke structural dynamics problems such as failures due to fatigue or sudden collapse by resonance and amplification.

scholarly journals Experimental and CFD Simulations of the Aerosol Flow in the Air Ventilating the Underground Excavation in Terms of SARS-CoV-2 Transmission

Energies ◽  
2021 ◽  
Vol 14 (16) ◽  
pp. 4743
Author(s):  
Tomasz Janoszek ◽  
Zbigniew Lubosik ◽  
Lucjan Świerczek ◽  
Andrzej Walentek ◽  
Jerzy Jaroszewicz
Keyword(s):  
Numerical Calculations ◽  
Mining Institute ◽  
Ventilation Network ◽  
Underground Excavation ◽  
In Situ Tests ◽  
Ansys Fluent ◽  
Aerosol Emission ◽  
Ansys Cfx ◽  
Computational Fluid Dynamics Cfd

The paper presents the results of experimental and model tests of transport of dispersed fluid droplets forming a cloud of aerosol in a stream of air ventilating a selected section of the underground excavation. The excavation selected for testing is part of the ventilation network of the Experimental Mine Barbara of the Central Mining Institute. For given environmental conditions, such as temperature, pressure, relative humidity, and velocity of air, the distribution of aerosol droplet changes in the mixture of air and water vapor along the excavation at a distance was measured at 10 m, 25 m, and 50 m from the source of its emission. The source of aerosol emission in the excavation space was a water nozzle that was located 25 m from the inlet (inlet) of the excavation. The obtained results of in situ tests were related to the results of numerical calculations using computational fluid dynamics (CFD). Numerical calculations were performed using Ansys-Fluent and Ansys-CFX software. The dimensions and geometry of the excavation under investigation are presented. The authors describe the adopted assumptions and conditions for the numerical model and discuss the results of the numerical solution.

Identification of Bearing Coefficients of Flexible Rotor-Bearing Systems

2000 ◽  
Author(s):  
Tachung Yang ◽  
Wei-Ching Chaung
Keyword(s):  
Industrial Applications ◽  
Operating Conditions ◽  
Least Square ◽  
Flexible Rotor ◽  
Fem Modeling ◽  
Identification Method ◽  
Reaction Forces ◽  
Manufacturing Assembly ◽  
Stiffness And Damping

The accuracy of stiffness and damping coefficients of bearings is critical for the rotordynamic analysis of rotating machinery. However, the influence of bearings depends on the design, manufacturing, assembly, and operating conditions of the bearings. Uncertainties occur quite often in manufacturing and assembly, which causes the inaccuracy of bearing predictions. An accurate and reliable in-situ identification method for the bearing coefficients is valuable to both analyses and industrial applications. The identification method developed in this research used the receptance matrices of flexible shafts from FEM modeling and the unbalance forces of trial masses to derive the displacements and reaction forces at bearing locations. Eight bearing coefficients are identified through a Total Least Square (TLS) procedure, which can handle noise effectively. A special feature of this method is that it can identify bearing coefficients at a specific operating speed, which make it suitable for the measurement of speed-dependent bearings, like hydrodynamic bearings. Numerical validation of this method is presented. The configurations of unbalance mass arrangements are discussed.

scholarly journals Current treatment of double hit and double expressor lymphoma

Hematology ◽  
2017 ◽  
Vol 2017 (1) ◽  
pp. 295-297 ◽  
Author(s):  
Patrick M. Reagan ◽  
Andrew Davies
Keyword(s):  
Cell Lymphoma ◽  
B Cell Lymphoma ◽  
Total Abdominal Hysterectomy ◽  
Abdominal Hysterectomy ◽  
Current Treatment ◽  
Current Data ◽  
Lymphoid Cells ◽  
High Grade ◽  
Computed Tomography Scans

Abstract A 60-year-old female presented with abdominal pain and distension. Following computed tomography scans of the abdomen and pelvis, she was taken urgently to the operating room, with the belief that she had appendicitis with perforation. At laparotomy, the findings were consistent with an ovarian carcinoma; there was extensive infiltration of the ovary, bowel, and omental deposits. Cytoreductive surgery was performed including total abdominal hysterectomy and bilateral salpingo-oophorectomy. The final pathology, however, revealed infiltration with medium-sized atypical lymphoid cells positive for CD20, CD10, MYC, BLC2, and BCL6 by immunohistochemistry. MYC and BCL2 translocations were identified by fluorescence in situ hybridization consistent with a diagnosis of high-grade B-cell lymphoma with rearrangements of MYC and BCL2. With the current data available, what is the optimal treatment of this patient?

Investigation of Small- to Large-Strain Moduli Correlations of Rockfill Materials – Application to Romaine-2 Dam

2021 ◽  
Author(s):  
Ibrahim Lashin ◽  
Michael Ghali ◽  
Marc Smith ◽  
Daniel Verret ◽  
Mourad Karray
Keyword(s):  
Large Strain ◽  
Deformation Behaviour ◽  
Numerical Data ◽  
Small Strain ◽  
Hyperbolic Model ◽  
Large Strains ◽  
Initial Modulus ◽  
Rockfill Materials ◽  
Materials Used

Establishment of a relationship between the shear wave velocity (Vs) and other geotechnical parameters of rockfill soils at large strains (oedometer modulus, Moedo, tangent modulus, Et) is considered a significant step towards more precise modelling of earth-structure deformation behaviour. In this study, four samples of different gradations, reconstituted from the rockfill materials used in the construction of the Romaine-2 dam, were experimented to correlate the small strain to large strain moduli. Development of Moedo and Vs with consolidation was measured in the laboratory using the piezoelectric ring-actuator technique (P-RAT) incorporated in a large oedometer. Therefore, a correlation between Moedo and small strain shear modulus Go was proposed. Moreover, numerical simulations were performed based on the Duncan-Chang hyperbolic model to correlate the Vs to Duncan-Chang initial modulus(Ei). Based on the experimental and numerical data, a relation between Ei and Vs of the tested rockfill has been established. Verification studies were also carried out on in-situ measurements during Romaine-2 dam construction, proofing the ability of the proposed relationships to predict Ei related to the minor principal stress (σ3) from in-situ Vs measurement. The proposed correlations could help the geotechnical designers to estimate accurately the deformation of rockfill materials from in-situ Vs measurement.

An Innovative Use of TDR Probes: First Numerical Validations with a Coaxial Cable

2018 ◽  
Vol 23 (4) ◽  
pp. 437-442
Author(s):  
Raffaele Persico ◽  
Iman Farhat ◽  
Lourdes Farrugia ◽  
Sebastiano D'Amico ◽  
Charles Sammut
Keyword(s):  
Magnetic Properties ◽  
Transmission Line ◽  
Time Domain ◽  
Numerical Data ◽  
Time Domain Reflectometry ◽  
Coaxial Cable ◽  
Transmission Line Model ◽  
Properties Of Materials

In this paper we propose a study regarding some possibilities that can be offered by a time domain reflectometry (TDR) probe in retrieving both dielectric and magnetic properties of materials. This technique can be of interest for several applications, among which the characterization of soil in some situations. In particular, here we propose an extension of the paper “Retrieving electric and magnetic propetries of the soil in situ: New possibilities”, presented at the IWAGPR, held in Edinburgh in 2017, and as a new contribution we will validate a transmission line model with numerical data simulated by the CST code.

scholarly journals Church enclosure walls bearing capacity estimations and its validation on 3D models

2020 ◽  
Vol 310 ◽  
pp. 00023
Author(s):  
Pavel Kuklik ◽  
Martin Valek ◽  
Ivana Bozulic ◽  
Pratik Gajjar ◽  
Chandrashekhar Mahato ◽  
...  
Keyword(s):  
Bearing Capacity ◽  
Numerical Models ◽  
3D Models ◽  
Present Calculation ◽  
Fem Modeling ◽  
Structural Element ◽  
Historical Structures ◽  
Numerical Tools ◽  
Tools And Techniques

The paper deals with the nonlinear computational modeling of the baroque enclosure masonry walls. The main tasks are input parameters for efficient advanced numerical tools and techniques, which are based on nonlinear and quasi brittle constitutive FEM modeling. For the work was used the knowledge and results from the Broumov Group Churches survey acquired in the frame of international SAHC university cooperation. The goal of the contribution are real bearing capacity parameters of the composite enclosure walls, which leads from standard homogenization techniques. With regards to the material micro modeling of different wall configuration in longitudinal and transversal direction was done with ATENA 2D software to evaluate the safe bearing capacity of the walls. The set of models aim to assess the bearing capacity of the enclosure wall, which is the main structural element in the church. In detail, we will present results from the numerical investigation, and partial in situ testing, from Vižňov, Ruprechtice and Otovice. Finally, we will present calculation of cracks propagation on full 3D church models. Concerning historical structures, it is one way how to validate the quality of estimations and validate numerical models.

scholarly journals Detection of 11q13 rearrangements in hematologic neoplasias by double- color fluorescence in situ hybridization

Blood ◽  
1996 ◽  
Vol 87 (4) ◽  
pp. 1512-1519 ◽  
Author(s):  
LJ Coignet ◽  
E Schuuring ◽  
RE Kibbelaar ◽  
TK Raap ◽  
KK Kleiverda ◽  
...  
Keyword(s):  
In Situ Hybridization ◽  
Fluorescence In Situ Hybridization ◽  
Hematologic Malignancies ◽  
Current Data ◽  
Lymphocytic Leukemia ◽  
Cell Nuclei ◽  
Interphase Cell ◽  
Interphase Cells ◽  
Chromosomal Breaks

Rearrangements within the chromosome 11q13 region are frequent in hematologic malignancies. 50% of 75% of mantle cell lymphomas (MCLs) carry a translocation t(11;14) (q13;q32). Using Southern blot analysis, a BCL1 breakpoint can be detected in approximately 50% of MCLs. It is not known whether other MCLs harbor also breakpoints at 11q13. Breakpoints in this region not involved in t(11;14), are detected in chronic lymphocytic leukemia and acute myeloid leukemia. To detect and localize breakpoints at 11q13 more accurately, we have developed fluorescence in situ hybridization using two probe sets of differently labeled cosmids, symmetrically localized at either side of the major translocation cluster of BCL1. These probes span a region of 450 to 750 kb. We applied this assay to a series of hematologic malignancies with 11q13 abnormalities identified by classical cytogenetics. All four samples with a t(11;14) (q13;q32) showed dissociation of the differently colored signals in metaphase and interphase cells, thereby indicating a chromosomal break in the region defined by the probe sets. The frequency of abnormal metaphase and interphase cells was comparable with that observed in any of the 13 malignancies with other chromosomal 11q13 abnormalities, indicating that these chromosomal breaks occurred outside the 450- to 750-kb region covered by the probes. One patient showed triplication and one patient showed monoallelic loss of this region. The current data show that double-color fluorescence in situ hybridization is a simple and reliable method for detection of the t(11;14)(q13;q32) in interphase cell nuclei and that is can be used to distinguish this translocation from other 11q13 rearrangements in hematologic malignancies.

Transient Simulation of Flow Past Smooth Circular Cylinder at very High Reynolds Number Using OpenFOAM

2014 ◽  
Vol 592-594 ◽  
pp. 1972-1977 ◽  
Author(s):  
Sangamesh M. Hosur ◽  
D.K. Ramesha ◽  
Suman Basu
Keyword(s):  
Reynolds Number ◽  
Circular Cylinder ◽  
Open Source ◽  
High Reynolds Number ◽  
Numerical Data ◽  
Flow Past ◽  
Computational Fluid Dynamics Cfd ◽  
High Reynolds ◽  
Set Up ◽  
Free Open Source

Flow past a smooth circular cylinder at high Reynolds number (Re=3.6 x 106) which covers the upper-transition regime has been investigated numerically by using Open source Field Operation and Manipulation (OpenFOAM) package. OpenFOAM is a free, open source Computational Fluid Dynamics (CFD) software package. The numerical model has been set up as two dimensional (2D), transient, incompressible and turbulent flow. A standard high Reynolds number k-ε turbulence model is included to evaluate the turbulence. The objective of the present work is to set up the case using pimpleFoam solver which is an Unsteady Reynolds Averaged Simulations (URANS) model and to evaluate the model for its conformance with available literature and experiments. The results obtained are compared with experimental and numerical data.

Numerical Simulation of Turbulent Flows in Ribbed Pipes

2005 ◽  
Author(s):  
Sowjanya Vijiapurapu ◽  
Jie Cui
Keyword(s):  
Turbulent Flows ◽  
Turbulence Models ◽  
Numerical Data ◽  
Reynolds Numbers ◽  
Navier Stokes ◽  
Friction Resistance ◽  
Circular Pipes ◽  
Computational Fluid Dynamics Cfd ◽  
Stress Models ◽  
Type Intermediate

The Reynolds averaged Navier-Stokes (RANS) equations were solved along with three turbulence models, namely κ-ε, κ-ω, and Reynolds stress models (RSM), to study the fully developed turbulent flows in circular pipes roughened by repeated square ribs. The spacing between the ribs was varied to form three representative types of surface roughness; d–type, intermediate, and k–type. Solutions of these flows at two Reynolds numbers were obtained using the commercial computational fluid dynamics (CFD) software Fluent. The numerical results were validated against experimental measurements and other numerical data published in literature. Extensive investigation of effects of rib spacing and Reynolds number on the pressure and friction resistance, flow and turbulence distribution was presented. The performance of three turbulence models was also compared and discussed.

Yaw Drift Moment of a Floating Structure in Waves

2005 ◽  
Author(s):  
Dimitris Spanos ◽  
Apostolos Papanikolaou
Keyword(s):  
Hydrodynamic Forces ◽  
Computational Method ◽  
Irregular Waves ◽  
Linear Potential ◽  
Floating Bodies ◽  
Floating Structure ◽  
Natural Wave ◽  
Positioning Systems ◽  
Floating Structures ◽  
Wave Induced

The wave induced yaw drift moment on floating structures is of particular interest when the lateral yaw motion of the structure should be controlled by moorings and/or active dynamic positioning systems. In the present paper, the estimation of the yaw drift moment in the modeled natural wave environment is conducted by application of a nonlinear time domain numerical method accounting for the motion of arbitrarily shaped floating bodies in waves. The computational method is based on linear potential theory and includes the non-linear hydrostatic terms in an exact way, whereas the higher-order wave-induced effects are partly approximated. Despite the approximate modeling of the second order hydrodynamic forces, the method proved to satisfactorily approach the dominant part of the exerted hydrodynamic forces enabling the calculation of drift forces and of other drift effects in irregular waves. Hence, the subject yaw drift moment in the modeled natural wave environment is derived, resulting to a basic reference for the design of similar type floating structures.

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