Iceberg Load Software Update Using 2019 Iceberg Profile Dataset

2021 ◽  
Author(s):  
Paul Stuckey ◽  
Mark Fuglem ◽  
Adel Younan ◽  
Hamid Shayanfar ◽  
Yujian Huang ◽  
...  
Keyword(s):  
Three Dimensional ◽  
Length Distribution ◽  
Interaction Model ◽  
Analysis Tool ◽  
Profile Data ◽  
Generic Structure ◽  
Software Update ◽  
Extreme Loads ◽  
Load Distributions ◽  
Wall Interaction

Abstract The Iceberg Loads Software (ILS) was developed initially to determine design iceberg loads for the Hebron Gravity Base Structure (GBS). The ILS framework has since been adapted for assessing iceberg loads on other structures such as the West White Rose Platform, subsea protection structures, pipelines laid on the seabed and floating production structures (spars and FPSOs). When the ILS was developed, the available iceberg geometry dataset (collected in the 1980s) was relatively limited, which required certain assumptions (i.e., flat wall interaction) and parametrizations (i.e., length distribution, length/draft/mass relationships, eccentricity, etc.) in the formulation of the interaction model. Renewed iceberg profile collection began in 2012, with ongoing improvements in the data collection methodology such that, of the 200 iceberg profiles collected from 2012 onwards, 134 were collected in 2019. The profile data were collected using LiDAR for the iceberg sail and multibeam sonar for the keel. The ILS has been updated using the recent three dimensional (3D) profiles, and a comparison of original versus updated iceberg load distributions for a generic structure show a decrease in loads. Updated ILS loads are compared with another iceberg load analysis tool that directly incorporates iceberg profile data rather than relying on some of the assumptions and parametrizations used in the original ILS formulation. This comparison shows some differences, particularly for extreme loads, which are the subject of on-going investigation.

DEVELOPMENT OF DROP/WALL INTERACTION MODEL FOR APPLICATION IN ENGINE CONDITIONS

2020 ◽  
Vol 30 (3) ◽  
pp. 153-170
Author(s):  
Yaoyu Pan ◽  
Xiufeng Yang ◽  
Song-Charng Kong ◽  
Chol-Bum M. Kweon
Keyword(s):  
Interaction Model ◽  
Wall Interaction

Thermomechanical Coupling of a Hyper-viscoelastic Truck Tire and a Pavement Layer and its Impact on Three-dimensional Contact Stresses

2021 ◽  
pp. 036119812110171
Author(s):  
Angeli Jayme ◽  
Imad L. Al-Qadi
Keyword(s):  
Contact Stress ◽  
Contact Area ◽  
Three Dimensional ◽  
Interaction Model ◽  
Rolling Resistance ◽  
Contact Stresses ◽  
Thermomechanical Coupling ◽  
Temperature Profiles ◽  
Near Surface ◽  
Truck Tire

A thermomechanical coupling between a hyper-viscoelastic tire and a representative pavement layer was conducted to assess the effect of various temperature profiles on the mechanical behavior of a rolling truck tire. The two deformable bodies, namely the tire and pavement layer, were subjected to steady-state-uniform and non-uniform temperature profiles to identify the significance of considering temperature as a variable in contact-stress prediction. A myriad of ambient, internal air, and pavement-surface conditions were simulated, along with combinations of applied tire load, tire-inflation pressure, and traveling speed. Analogous to winter, the low temperature profiles induced a smaller tire-pavement contact area that resulted in stress localization. On the other hand, under high temperature conditions during the summer, higher tire deformation resulted in lower contact-stress magnitudes owing to an increase in the tire-pavement contact area. In both conditions, vertical and longitudinal contact stresses are impacted, while transverse contact stresses are relatively less affected. This behavior, however, may change under a non-free-rolling condition, such as braking, accelerating, and cornering. By incorporating temperature into the tire-pavement interaction model, changes in the magnitude and distribution of the three-dimensional contact stresses were manifested. This would have a direct implication on the rolling resistance and near-surface behavior of flexible pavements.

Effect of Spray-Wall Interaction On Thermoacoustic Instability Prediction by Flame Transfer Function and the Convective Time Delay Method

2021 ◽  
Author(s):  
Sheng Meng ◽  
Man Zhang
Keyword(s):  
Time Delay ◽  
Transfer Function ◽  
Numerical Models ◽  
Time Lag ◽  
Interaction Model ◽  
Phase Lag ◽  
Thermoacoustic Instability ◽  
Spray Flame ◽  
Wall Interaction ◽  
Definition Of

Abstract This study numerically investigates the effect of spray-wall interactions on thermoacoustic instability prediction. The LES-based flame transfer function (FTF) and the convective time delay methods are used by combining the Helmholtz acoustic solver to predict a single spray flame under the so-called slip and film spray-wall conditions. It is found that considering more realistic film liquid and a wall surface interaction model achieves a more accurate phase lag in both of the time lag evaluations compared to the experimental results. Additionally, the results show that a new time delay exists between the liquid film fluctuation and the unsteady heat release, which explains the larger phase value in the film spray-wall condition than in the slip condition. Moreover, the prediction capability of the FTF framework and the convective time delay methodology in the linear regime are also presented. In general, the instability frequency differences predicted using the FTF framework under the film condition are less than 10 Hz compared with the experimental data. However, an underestimation of the numerical gain value leads to requiring a change in the forcing position and an improvement in the numerical models. Due to the ambiguous definition of the gain value in the convective time delay method, this approach leads to arbitrary and uncertain thermoacoustic instability predictions.

An Automated CFD Design and Analysis Tool for Inlet-Bleed Systems

1998 ◽  
Author(s):  
Tom I-P. Shih ◽  
Yu-Liang Lin ◽  
Andrew J. Flores ◽  
Mark A. Stephens ◽  
Mark J. Rimlinger ◽  
...  
Keyword(s):  
Boundary Layer ◽  
Three Dimensional ◽  
Incident Shock ◽  
Navier Stokes ◽  
Oblique Shock Wave ◽  
Design Parameters ◽  
Analysis Tool ◽  
Cfd Analysis ◽  
Circular Holes ◽  
Embedded Grids

Abstract A pre-processor was developed to assist CFD experts and non-experts in performing steady, three-dimensional Navier-Stokes analysis of a class of inlet-bleed problems involving oblique shock-wave/ boundary-layer interactions on a flat plate with bleed into a plenum through rows of circular holes. With this pre-processor, once geometry (e.g., hole dimensions and arrangement) and flow conditions (e.g., Mach number, boundary-layer thickness, incident shock location) are inputted, it will automatically generate every file needed to perform a CFD analysis from the grid system to initial and boundary conditions. This is accomplished by accessing a knowledge base established by experts who understand both CFD and the class of problems being analyzed. For experts in CFD, this tool greatly reduces the amount of time and effort needed to setup a problem for CFD analysis. It also provides experts with knobs to make changes to the setup if desired. For non-experts in CFD, this tool enables reliable and correct usage of CFD. A typical session on a workstation from data input to the generation of all files needed to perform a CFD analysis involves less than ten minutes. This pre-processor, referred to as AUTOMAT-V2, is an improved version of a code called AUTOMAT. Improvements made include: (1) multi-block structured grids can be patched in addition to being overlapped; (2) embedded grids can be introduced near bleed holes to reduce the number of grid points/cells needed by a factor of up to four; (3) grid systems generated allow up to three levels of multigrid; (4) CFL3D is supported in addition to OVERFLOW, two well-known and highly regarded Navier-Stokes solvers developed at NASA’s Langley and Ames Research Centers; (5) all files needed to run RONNIE for patched grids and MAGGIE for overlapped grids are also generated; and (6) more design parameters can be investigated including the study of micro bleed and effects of flow/hole misalignments.

Numerical Simulation Of A Microchannel For Microelectronic Cooling

2012 ◽  
Author(s):  
Wai Hing Wong ◽  
Normah Mohd. Ghazali
Keyword(s):  
Heat Transfer ◽  
Numerical Simulation ◽  
Heat Flux ◽  
Aspect Ratio ◽  
Three Dimensional ◽  
Large Temperature ◽  
Rectangular Microchannel ◽  
Numerical Work ◽  
Solid Region ◽  
Wall Interaction

Kertas kerja ini membincangkan simulasi berangka ke atas sinki haba saluran mikro dalam penyejukan alatan mikroelektronik. Model Dinamik Bendalir Berkomputer (CFD) tiga dimensi dibina menggunakan pakej komersil, FLUENT, untuk mengkaji fenomenon aliran bendalir dan pemindahan haba konjugat di dalam suatu sinki haba segi empat yang diperbuat daripada silikon. Model ditentusahkan dengan keputusan daripada uji kaji dan pengkajian berangka yang lepas untuk lingkungan nombor Reynolds kurang daripada 400 berdasarkan diameter hidraulik 86 mm. Kajian ini mengambil kira kesan kelikatan bendalir yang bersandaran dengan suhu dan keadaan aliran pra–membangun dari segi hidrodinamik dan haba. Model memberi maklumat tentang taburan suhu dan fluks haba yang terperinci di dalam sinki haba saluran mikro. Kecerunan suhu yang tinggi dicatat pada kawasan pepejal berdekatan dengan sumber. Fluks haba paling tinggi didapati pada dinding tepi saluran mikro diikuti oleh dinding atas dan bawah. Purata pekali pemindahan haba yang lebih tinggi bagi silikon menjadikan ia bahan binaan sinki haba saluran mikro yang lebih baik berbanding dengan kuprum dan aluminium. Peningkatan nisbah aspek saluran mikro yang bersegi empat memberi kecekapan penyejukan yang lebih tinggi kerana kelebaran saluran yang berkurangan memberi kecerunan halaju yang lebih tinggi dalam saluran. Nisbah aspek yang optimum yang diperoleh adalah dalam lingkungan 3.7 – 4.1. Kata kunci: Saluran mikro, CFD, FLUENT, simulasi berangka, penyejukan mikroelektron The paper discusses the numerical simulation of a micro–channel heat sink in microelectronics cooling. A three–dimensional Computational Fluid Dynamics (CFD) model was built using the commercial package, FLUENT, to investigate the conjugate fluid flow and heat transfer phenomena in a silicon–based rectangular microchannel heatsink. The model was validated with past experimental and numerical work for Reynolds numbers less than 400 based on a hydraulic diameter of 86 mm. The investigation was conducted with consideration of temperaturedependent viscosity and developing flow, both hydrodynamically and thermally. The model provided detailed temperature and heat flux distributions in the microchannel heatsink. The results indicate a large temperature gradient in the solid region near the heat source. The highest heat flux is found at the side walls of the microchannel, followed by top wall and bottom wall due to the wall interaction effects. Silicon is proven to be a better microchannel heatsink material compared to copper and aluminum, indicated by a higher average heat transfer. A higher aspect ratio in a rectangular microchannel gives higher cooling capability due to high velocity gradient around the channel when channel width decreases. Optimum aspect ratio obtained is in the range of 3.7 – 4.1. Key words: Microchannel, CFD, FLUENT, numerical simulation, microeletronics cooling

Numerical Simulation on Mooring Performance of LNG-FPSO System in Realistic Seas

2005 ◽  
Author(s):  
Yoshiyuki Inoue ◽  
Md. Kamruzzaman
Keyword(s):  
Time Domain ◽  
Oil And Gas ◽  
Three Dimensional ◽  
Time Domain Analysis ◽  
Analysis Tool ◽  
Motion Response ◽  
Non Linear ◽  
Floating System ◽  
Exciting Forces ◽  
The Time Domain

The LNG-FPSO concept is receiving much attention in recent years, due to its active usage to exploit oil and gas resources. The FPSO offloads LNG to an LNG carrier that is located close to the FPSO, and during this transfer process two large vessels are in close proximity to each other for daylong periods of time. Due to the presence of neighboring vessel, the motion response of both the vessels will be affected significantly. Hydrodynamic interactions related to wave effects may result in unfavorable responses or the risk of collisions in a multi-body floating system. Not only the motion behavior but also the second order drift forces are influenced by the neighboring structures due to interactions of the waves among the structures. A study is made on the time domain analysis to assess the behavior and the operational capability of the FPSO system moored in the sea having an LNG carrier alongside under environmental conditions such as waves, wind and currents. This paper presents an analysis tool to predict the dynamic motion response and non-linear connecting and mooring forces on a parallel-connected LNG-FPSO system due to non-linear exciting forces of wave, wind and current. Simulation for the mooring performance is also investigated. The three-dimensional source-sink technique has been applied to obtain the radiation forces and the transfer function of wave exciting forces on floating multi-bodies. The hydrodynamic interaction effect between the FPSO and the LNG carrier is included to calculate the hydrodynamic forces. For the simulation of a random sea and also for the generation of time depended wind velocity, a fully probabilistic simulation technique has been applied. Wind and current loads are estimated according to OCIMF. The effects of variations in wave, wind and current loads and direction on the slowly varying oscillations of the LNG and FPSO are also investigated in this paper. Finally, some conclusions are drawn based on the numerical results obtained from the present time domain simulations.

Impact of image reconstruction parameters when using 3D DSA reconstructions to measure intracranial aneurysms

2017 ◽  
Vol 10 (3) ◽  
pp. 285-289 ◽  
Author(s):  
Katrina L Ruedinger ◽  
David R Rutkowski ◽  
Sebastian Schafer ◽  
Alejandro Roldán-Alzate ◽  
Erick L Oberstar ◽  
...  
Keyword(s):  
Three Dimensional ◽  
Hounsfield Unit ◽  
Ground Truth ◽  
Individual Case ◽  
Dome Height ◽  
Patient Specific ◽  
Analysis Tool ◽  
Accuracy Of Measurements ◽  
Image Characteristic

Background and purposeSafe and effective use of newly developed devices for aneurysm treatment requires the ability to make accurate measurements in the angiographic suite. Our purpose was to determine the parameters that optimize the geometric accuracy of three-dimensional (3D) vascular reconstructions.MethodsAn in vitro flow model consisting of a peristaltic pump, plastic tubing, and 3D printed patient-specific aneurysm models was used to simulate blood flow in an intracranial aneurysm. Flow rates were adjusted to match values reported in the literature for the internal carotid artery. 3D digital subtraction angiography acquisitions were obtained using a commercially available biplane angiographic system. Reconstructions were done using Edge Enhancement (EE) or Hounsfield Unit (HU) kernels and a Normal or Smooth image characteristic. Reconstructed images were analyzed using the vendor's aneurysm analysis tool. Ground truth measurements were derived from metrological scans of the models with a microCT. Aneurysm volume, surface area, dome height, minimum and maximum ostium diameter were determined for the five models.ResultsIn all cases, measurements made with the EE kernel most closely matched ground truth values. Differences in values derived from reconstructions displayed with Smooth or Normal image characteristics were small and had only little impact on the geometric parameters considered.ConclusionsReconstruction parameters impact the accuracy of measurements made using the aneurysm analysis tool of a commercially available angiographic system. Absolute differences between measurements made using reconstruction parameters determined as optimal in this study were, overall, very small. The significance of these differences, if any, will depend on the details of each individual case.

Development of Iceberg Profiling Technology

2021 ◽  
Author(s):  
Jonathon Bruce ◽  
Renat Yulmetov ◽  
Tony King ◽  
Freeman Ralph ◽  
Adel Younan
Keyword(s):  
Large Scale ◽  
Analysis Tool ◽  
Profile Data ◽  
Grand Banks ◽  
Drift Model ◽  
Iceberg Drift ◽  
Large Scale Field ◽  
Loads Analysis ◽  
Rapid Generation ◽  
The Stability

Abstract Iceberg management on the Grand Banks of Newfoundland, Canada is currently carried out without knowledge of the underwater shape of the iceberg. An iceberg profiling system is being developed to integrate the rapid generation of 3D iceberg shape data with a collection of tools that utilize the data to provide recommendations, intended to improve iceberg management effectiveness. The intent is for the system to be operated by vessel crew with minimal training. The system utilizes a LiDAR and a pole mounted multibeam sonar to profile the iceberg sail and keel, respectively. A vessel equipped with the profiling system circles an iceberg twice to collect a profile, a process that on average requires approximately 15–30 minutes. The data is collected in the form of a point cloud, which must be de-noised and corrected for both drift and rotation of the iceberg. Tools have been developed to assess the stability of the iceberg, and to consider the shape of the iceberg relative to towing net dimensions, to provide guidance to the operator regarding the recommended towing direction to avoid iceberg rolling or net slippage events. Other applications of the profile data include an impact loads analysis tool that determines the distribution of potential iceberg loads in the event of a collision with a given platform, and an operational iceberg drift model that uses the iceberg shape to improve iceberg drift forecasts. Large-scale field programs were carried out in both 2018 and 2019 as part of the development process for the system. Data collected has shown that iceberg characteristics have changed significantly when compared to iceberg profile data collected in the 1980s. For a given iceberg waterline length, the more recent data shows significantly reduced drafts. The 1980s iceberg dataset currently dominates the data used as the basis for assessing iceberg loads on surface facilities and iceberg risk to subsea assets. Reduced iceberg drafts will result in reduced risk to subsea facilities and pipelines. These results and observations demonstrate the usefulness of the iceberg profiling system as an environmental monitoring tool, and the data collected has design and operational applications. The development and capabilities of the system are presented, as well as the comparison of the 1980’s and newer iceberg datasets and implications for iceberg risk to facilities on the Grand Banks and surrounding regions.

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