Predicting Loads on a LNG Carrier With CFD

2010 ◽  
Author(s):  
Fahd Fathi ◽  
Christiaan Klaij ◽  
Arjen Koop
Keyword(s):  
Mathematical Models ◽  
Model Test ◽  
Offshore Structures ◽  
Physical Parameters ◽  
Test Results ◽  
Factors Influencing ◽  
Current Affairs ◽  
Physical And Mathematical Models ◽  
Scale Data

The Current Affairs Joint Industry Project was initiated to develop the understanding and tools for the assessment of current loads on offshore structures. CFD is one of these tools requiring a good understanding of the underlying physical and mathematical models. In order to assess its suitability for the prediction of current loads on monohulls, the flow around a LNG carrier for which model scale data is available was considered. The LNG carrier, including bilge–keels and rudder, was towed at scale 1/50 in Marin’s shallow water basin during the HAWAI JIP, for flow angles between 0 and 180 degrees. The measurements were shared with the Current Affairs JIP, for which the participants were invited to perform CFD computations reproducing the model test results. A number of these simulations are presented in this paper. The analysis of the results includes discussion on the grid generation as well as the numerical and physical parameters of the simulation. The comparison between experiments and computations shows that CFD can provide good qualitative predictions for the variation of force coefficients with inflow angle. The origin of the result variability between the participants is discussed and attention is drawn to the different factors influencing the quality of the simulation.

Horizontal Capacity of Embedded Suction Anchors in Clay

2010 ◽  
Vol 133 (1) ◽  
Author(s):  
S. Bang ◽  
K. Jones ◽  
Y. S. Kim ◽  
Y. Cho
Keyword(s):  
Analytical Solution ◽  
Model Test ◽  
Soil Type ◽  
Embedment Depth ◽  
Centrifuge Model Test ◽  
Test Results ◽  
Pullout Capacity ◽  
Direct Function ◽  
Centrifuge Model ◽  
Factors Influencing

The embedded suction anchor (ESA) is a type of permanent offshore foundation that is installed by a suction pile. The primary factors influencing the horizontal pullout capacity of an ESA include the loading point, the soil type, the embedment depth, and the addition of flanges. The main purpose of this study is to develop an analytical solution that is capable of estimating the horizontal pullout capacity of ESAs with the loading point being anywhere along its length with or without flanges. An analytical solution has been developed to estimate the horizontal pullout capacity of embedded suction anchors in clay seafloor. Validation has been made through comparisons with the centrifuge model test results. Results indicate that the horizontal pullout capacity of the embedded suction anchor in clay increases, reaches its peak, and then starts to decrease as the point of the load application moves downward. The effect of flanges on the horizontal pullout capacity is also found to be significant. The horizontal pullout capacity is a direct function of the loading point. The horizontal pullout capacity increases as the loading point moves downward and the maximum pullout capacity is obtained when the loading point is approximately at the mid-depth. The increase in horizontal pullout capacity can be significant, i.e., more than twice in magnitude when the maximum pullout capacity is compared with that associated with the loading point near the top or tip.

Stochastic Linearization and its Application in Motion Analysis of Cylindrical Floating Structure With Bilge Boxes

2016 ◽  
Author(s):  
Yan-Lin Shao ◽  
Jikun You ◽  
Einar Bernt Glomnes
Keyword(s):  
Motion Analysis ◽  
Model Test ◽  
Added Mass ◽  
Offshore Structures ◽  
Test Results ◽  
Viscous Effects ◽  
Natural Period ◽  
Stochastic Linearization ◽  
Excitation Force ◽  
Drag Term

To account for the viscous effects of damping devices, for instance, bilge keels or bilge boxes, on the motions of ships and offshore structures, Morison’s equation is often adopted as an empirical but practical approach in the design process. In order to combine the standard engineering panel method with the drag term in Morison’s equation, and remain in the frequency domain, the drag term has to be linearized based on, for instance, stochastic linearization. In this paper, the stochastic linearization scheme is implemented in an in-house code and verified through the comparison with the DNV GL software WADAM. The model test results of a large cylindrical FPSO with bilge box are used to calibrate the drag coefficients in the Morison’s equation. When the linearized drag forces are included, heave motion RAOs correspond better to the model test results. However, the predicted natural periods of heave motions are seen to be smaller than those obtained from model tests. It is suspected that the viscous flow separation around the bilge box increases the added mass of the unit beyond what is predicted by potential flow alone. Discussions are made on the effect of viscous added mass on the heave natural period. It is quite common to only include the damping effects in the motion analysis for large offshore structures and ignore the contribution of the viscous effects on the excitation force. For the considered cylindrical FPSO, this paper demonstrates that the viscous excitation force can be important in survival conditions.

scholarly journals Model-Scale/Full-Scale Correlation of NRC-OCRE’s Model Resistance, Propulsion and Maneuvering Test Results

2015 ◽  
Author(s):  
Michael Lau
Keyword(s):  
Test Data ◽  
Model Test ◽  
Model Tests ◽  
Full Scale ◽  
Test Results ◽  
Sea Trial ◽  
Model Scale ◽  
Performance Predictions ◽  
Ice Strength ◽  
Scale Data

There are a variety of model ices and test techniques adopted by model test facilities. Most often, the clients would ask: “How well can you predict the full scale performance from your model test results?” Model-scale/full-scale correlation becomes an important litmus test to validate a model test technique and its results. This paper summarizes the model-scale/full-scale correlation performed on model test data generated at the National Research Council - Ocean, Coastal, and River Engineering’s (NRC-OCRE) test facility in St. John’s. This correlation includes ship performance predictions, i.e., resistance, propulsion and maneuvering. Selected works from NRC-OCRE on the USCGC icebreaker Healy, the CCGS icebreaker Terry-Fox, the CCGS R-Class icebreakers Pierre Radisson and Sir John Franklin and the CCGS icebreaker Louis S. St. Laurent were reviewed and summarized. The model tests were conducted at NRC-OCRE’s ice tank with the correct density (CD) EGADS model ice. This correlation is based on the concept that a “correlation friction coefficient” (CFC) can be used to predict full-scale ship icebreaking resistance from model test data. The CFCs have been compared for correlation studies using good-quality full-scale information for the five icebreaker models in the NRC-OCRE’s model test database. The review has shown a good agreement between NRCOCRE’s model test predictions and full-scale measurements. The resistance and power correlation were performed for five sets of full-scale data. Although there is substantial uncertainty on ice thickness and ice strength within the full scale data sets that contributes to data scattering, the data suggest a conservative estimate can be obtained to address reasonably this uncertainty by increasing the model prediction by 15% that envelopes most data points. Limited correlation for maneuvering in ice was performed for the USCGC icebreaker Healy. Selected test conditions from the sea trials were duplicated for the maneuvering tests and turning diameters were measured from the arcs of partial circles made in the ice tank. Performance predictions were then compared to the full-scale data previously collected. Despite some discrepancy in ice strength and power level between the model tests and sea trial, the model data agree well with the sea trial data except for three outliers. Otherwise, the maneuvering data show a good correlation between the model test and sea trial results.

scholarly journals The Effect of Leachate Waters on the Quality of Free Groundwater in Air Dingin Landfill, Padang City

2019 ◽  
Vol 3 (1) ◽  
pp. 62-66
Author(s):  
Takdir Alamsyah ◽  
Eri Barlian ◽  
Nurhasan Syah
Keyword(s):  
Water Quality ◽  
Pollution Control ◽  
Government Regulation ◽  
Quality Standard ◽  
Physical Parameters ◽  
Test Results ◽  
Quality Of Water ◽  
Analysis Technique ◽  
Leachate Water

The purpose of this study is 1) to know the condition of physical parameters, free groundwater chemistry; 2) to what extent of leachate water contamination of against free groundwater in the Air Dingin landfill, Padang City. The data analysis technique used in this study is based on Minister of Health Regulation Number 419/1990 concerning Water Quality Requirements and Supervision, and Government Regulation Number 82/2010 concerning Management of Water Quality and Water Pollution Control. The water quality physics test results show 1) smell and taste meet the quality standard requirements; 2) water temperature meets quality standard requirements; 3) watercolour meets quality standard requirements; 4) Dissolved Solids (TDS) meet the quality standard requirements; and 5) Suspended Solids (TSS) meet the quality standard requirements, while the chemical quality of water shows 1) pH below the quality standard; 2) Arsenic below the quality standard; 3) Cadmium is below the quality standard; 4) Chromium below the quality standard; 5) Iron below the quality standard; 6) Lead below the quality standard; 7) Manganese below the quality standard; 8) Free groundwater below the quality standard; and 9) COD below the quality standard.. Leachate water that comes out laterally from the garbage pile tends to flow following the contour of the land towards a lower direction.

On the Distribution of Wave Impact Loads on Offshore Structures

2017 ◽  
Author(s):  
Thomas B. Johannessen ◽  
Øystein Lande ◽  
Øistein Hagen
Keyword(s):  
Model Test ◽  
Load Distribution ◽  
Impact Load ◽  
Peak Load ◽  
Offshore Structures ◽  
Impact Loads ◽  
Test Results ◽  
Wave Impact ◽  
The Impact ◽  
Crest Height

For offshore structures in harsh environments, horizontal wave impact loads should be taken into account in design. Shafts on GBS structures, and columns on semisubmersibles and TLPs are exposed to impact loads. Furthermore, if the crest height exceeds the available freeboard, the deck may also be exposed to wave impact loads. Horizontal loads due to waves impacting on the structure are difficult to quantify. The loads are highly intermittent, difficult to reproduce in model tests, have a very short duration and can be very large. It is difficult to calculate these loads accurately and the statistical challenges associated with estimating a value with a prescribed annual probability of occurrence are formidable. Although the accurate calculation of crest elevation in front of the structure is a significant challenge, industry has considerable experience in handling this problem and the analysis results are usually in good agreement with model test results. The present paper presents a statistical model for the distribution of horizontal slamming pressures conditional on the incident crest height upwave of the structure. The impact load distribution is found empirically from a large database of model test results where the wave impact load was measured simultaneously at a large number of panels together with the incident crest elevation. The model test was carried out on a circular surface piercing column using long simulations of longcrested, irregular waves with a variety of seastate parameters. By analyzing the physics of the process and using the measured crest elevation and the seastate parameters, the impact load distribution model is made seastate independent. The impact model separates the wave impact problem in three parts: – Given an incident crest in a specified seastate, calculate the probability of the crest giving a wave impact load above a threshold. – Given a wave impact event above a threshold, calculate the distribution of the resulting peak load. – Given a peak load, calculate the distribution of slamming pressures at one spatial location. The development of the statistical model is described and it is shown that the model is appropriate for fixed and floating structures and for wave impact with both columns and the deck box.

scholarly journals Conditions of Substrate and Water Quality Supporting Activites as A Growth Factor in Mangrove at Coastal Basaan I, South East District Minahasa

2014 ◽  
Vol 1 (4) ◽  
pp. 204 ◽  
Author(s):  
Adnan S. Wantasen
Keyword(s):  
Water Quality ◽  
Mangrove Ecosystem ◽  
Physical Parameters ◽  
Test Results ◽  
Contributing Factors ◽  
Environmental Capacity ◽  
Organic C ◽  
The Village ◽  
Substrate Ph

Mangrove forest vegetation contained in Basaan The village has an important role, both ecologically and economically for the community. The mangrove ecosystem's ability to maintain its ecological function depends on factors - environmental contributing factors, namely the quality of the environment and substrate conditions. The purpose of the study was to measure the quality of environmental factors and substrate waters around mangrove and describe the environmental capacity of water at mangrove ecosystem. The method of research by sampling at two locations: station A and station B by taking water samples in which the chemical and physical parameters of the test carried out in the Laboratory of Water archipelago and substrate samples which were tested in Laborarotium Soil Fertility, Faculty of Agriculture Unsrat Manado. The test results showed that the water temperature is 310C and TSS levels <1 (station A) and 44 (station B), pH 7.3; salinity 32; NH3 0.26 (A), 0.05 (B); PO4 0.122 (A ), 0.013 (B); H2S < 0.02; DO 10.10 (A), 8.95 (B). For the test results is the basic substrate pH H2O 7.6 (station A) and 7.5 (station B) neutral category; pH KCl 5.1 (A) and 5.4 (B) neutral category, N 0.44 (A ), 0.34 (B) medium category; P2O5 1.98 (A) and 15.35 (B) medium category; organic C-5.83 (A) and 3.98 (B) high category; K2O 2, 27 (A) and 23.48 (B) medium category. Conditions coastal waters village Basaan I still quite good because of the support and the dukungya still need attention orthoposphat parameter whose value is higher than the standard.   Keywords : water quality, substrate base, carrying capacity

Customer’s satisfaction on service quality at Vietnam Technological and Commercial Joint Stock Bank – An Giang Branch

2020 ◽  
Vol 4 (3) ◽  
pp. First
Author(s):  
Tran Minh Hieu ◽  
Nguyen Duong Ngoc Mai Chi
Keyword(s):  
Customer Satisfaction ◽  
Service Quality ◽  
Test Method ◽  
Quality Of Services ◽  
Factors Affecting ◽  
Factors Influencing ◽  
Alpha Reliability ◽  
Survey Results ◽  
Development Orientation

This study applied SERVQUAL scale of Parasuraman et al to measure factors affecting customer satisfaction on service quality at Vietnam Technological and Commercial Joint Stock Bank - An Giang Branch (Techcombank An Giang). The study was conducted to survey 207 customers who have been using the service at Techcombank An Giang. The survey results were analyzed by the Cronbach's Alpha reliability test method, then used Exploratory factor analysis (EFA) to verify and evaluate the scale of service quality. The results of the regression analysis show that customer's satisfaction about service quality at Techcombank An Giang includes four factors: The factor with the highest level is the Empathy with Beta = 0.253, the second of factor is the Responsibility with Beta = 0.248, ranked third in the influence level is the Tangible with Beta = 0.235, and the lowest impact level is the Reliability with Beta = 0.144. The research also uses statistical methods to describe and test the differences of demographic factors with customer's satisfactionon service quality.The analysis results show that there is no difference between customer's satisfaction on service quality and factors such as gender, age, income, number of transaction banks, regular transaction banks, and time to use the service at Techcombank An Giang. Through the research results, the author would like to propose some ideas to improve the quality of services, thereby attracting new customers and importantly, keeping traditional customers because the development orientation of Techcombank is to take care of old customers to cross sell other products of the bank. The Stud results offer a basis for the branch to identify the factors influencing customer satisfaction on their service quality, thereby having an appropriate strategy to improve customer satisfaction.

Implementasi Voip Server Berbasis IPV6 Dengan Raspberry PI

2019 ◽  
Vol 9 (01) ◽  
pp. 47-54
Author(s):  
Rabbai San Arif ◽  
Yuli Fitrisia ◽  
Agus Urip Ari Wibowo
Keyword(s):  
Internet Protocol ◽  
Wireless Transmission ◽  
Raspberry Pi ◽  
Test Results ◽  
Average Delay ◽  
Ipv6 Network ◽  
Ip Network ◽  
Selection Of ◽  
Better Than

Voice over Internet Protocol (VoIP) is a telecommunications technology that is able to pass the communication service in Internet Protocol networks so as to allow communicating between users in an IP network. However VoIP technology still has weakness in the Quality of Service (QoS). VOPI weaknesses is affected by the selection of the physical servers used. In this research, VoIP is configured on Linux operating system with Asterisk as VoIP application server and integrated on a Raspberry Pi by using wired and wireless network as the transmission medium. Because of depletion of IPv4 capacity that can be used on the network, it needs to be applied to VoIP system using the IPv6 network protocol with supports devices. The test results by using a wired transmission medium that has obtained are the average delay is 117.851 ms, jitter is 5.796 ms, packet loss is 0.38%, throughput is 962.861 kbps, 8.33% of CPU usage and 59.33% of memory usage. The analysis shows that the wired transmission media is better than the wireless transmission media and wireless-wired.

UJI TARIK HIDRODINAMIKMODEL KAPAL BERSAYAP WiSE DENGAN LAMBUNG DASAR BERSTEP

2013 ◽  
Vol 12 (3) ◽  
Author(s):  
Iskendar Iskendar ◽  
Andi Jamaludin ◽  
Paulus Indiyono
Keyword(s):  
Comparative Study ◽  
Model Test ◽  
Hydrodynamic Model ◽  
Surface Effect ◽  
Center Of Gravity ◽  
Test Results ◽  
Flat Bottom ◽  
Towing Tank ◽  
Test Models ◽  
Wetted Surface Area

This paper describes hydrodynamic model tests of Wing in Surface Effect (WiSE) Craft. These craft  was fitted with  stephull  form in different location on longitudinal flat bottom (stepedhull planning craft) to determine the influences of sticking and porpoising motion performances. These motions are usually occured when the craft start to take-off from water surfaces. The test models with scale of 1 : 7 were comprised of 4 (four) stephull models and 1 (one) non-stephull model  as a comparative study. The hydrodynamic  tests were performed with craft speed of 16 – 32 knots (prototype values) in Towing Tank at UPT. Balai Pengkajian dan Penelitian Hidrodinamika (BPPH), BPPT, Surabaya. The resistance (drag) was measured by dynamo meter and the trim of model (draft changing at fore and aft  of model due to model speed) was measured by trim meter. By knowing the value of model trim, the wetted surface area can be determined. Then, the lift forces were calculated based on these measured values. The model test results were presented on tables and curves.  Test results show that models  with step located far away from center of gravity of the WiSE craft tend to porpoising and sticking condition, except if the step location on the below of these center of gravity. While model without step tends to sticking conditions.

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