scholarly journals Prediction of an Optimum Total Resistance Coefficient on Catamaran using Design of Experiment (DOE) Incorporated with CFD Approach

2020 ◽  
Vol 3 (1) ◽  
pp. 74-83
Author(s):  
Ahmad Fitriadhy ◽  
Sun Yin Lim ◽  
Adi Maimun
Keyword(s):  
Froude Number ◽  
Design Of Experiment ◽  
Cfd Simulation ◽  
Fluid Dynamic ◽  
Resistance Coefficient ◽  
Primary Objective ◽  
Design Stage ◽  
Total Resistance ◽  
Cfd Modelling ◽  
Simulation Results

In presence of complex hydrodynamic interferences between two demihulls on a catamaran ship has been prone to have a reliable prediction to her optimum total resistance. To achieve this, the author presents a Computational Fluid Dynamic (CFD) modelling incorporated with Design of Experiment (DOE) approach. Several parameters such as effect of Froude number ( ) with respect to various lateral separation ratios (S/L) of the catamaran have been taken into account. Here, the optimum total resistance coefficient (CT) has been mainly set within the range of S/L ratio 0.2 ≤ S/L ≤ 0.4 associated with Froude number 0.56 ≤  ≤ 0.66. The primary objective function of this optimization model has led towards minimizing a drag force and increased a lift force with respect to the above S/L ratios. In general, the simulation results had seemed quantitative similarity values for the optimum  of 0.6589, 0.6599 and 0.6596 with S/L ratios of 0.2, 0.3 and 0.4, respectively. In the case of  = 0.56, the optimum S/L ratios of 0.2993 and 0.3988 have resulted in insignificant reduction of CT by 0.62% and 0.32% as compared to S/L of 0.3 and 0.4, respectively. Similarly, the optimum S/L ratios of 0.2750 and 0.3750 with  = 0.66 have led to reduce by 0.14% and 0.46% as compared to S/L of 0.3 and 0.4, respectively. This CFD simulation results are very useful as preliminary data for the optimised ship resistance, which is mainly required to predict a ship powering in the early design stage.

scholarly journals Methodology for Computational Fluid Dynamic Validation for Medical Use: Application to Intracranial Aneurysm

2017 ◽  
Vol 139 (12) ◽  
Author(s):  
Nikhil Paliwal ◽  
Robert J. Damiano ◽  
Nicole A. Varble ◽  
Vincent M. Tutino ◽  
Zhongwang Dou ◽  
...  
Keyword(s):  
Flow Field ◽  
Intracranial Aneurysm ◽  
Cfd Simulation ◽  
Fluid Dynamic ◽  
Model Error ◽  
Patient Specific ◽  
Cfd Validation ◽  
Validation Data ◽  
Promising Tool ◽  
Simulation Results

Computational fluid dynamics (CFD) is a promising tool to aid in clinical diagnoses of cardiovascular diseases. However, it uses assumptions that simplify the complexities of the real cardiovascular flow. Due to high-stakes in the clinical setting, it is critical to calculate the effect of these assumptions in the CFD simulation results. However, existing CFD validation approaches do not quantify error in the simulation results due to the CFD solver’s modeling assumptions. Instead, they directly compare CFD simulation results against validation data. Thus, to quantify the accuracy of a CFD solver, we developed a validation methodology that calculates the CFD model error (arising from modeling assumptions). Our methodology identifies independent error sources in CFD and validation experiments, and calculates the model error by parsing out other sources of error inherent in simulation and experiments. To demonstrate the method, we simulated the flow field of a patient-specific intracranial aneurysm (IA) in the commercial CFD software star-ccm+. Particle image velocimetry (PIV) provided validation datasets for the flow field on two orthogonal planes. The average model error in the star-ccm+ solver was 5.63 ± 5.49% along the intersecting validation line of the orthogonal planes. Furthermore, we demonstrated that our validation method is superior to existing validation approaches by applying three representative existing validation techniques to our CFD and experimental dataset, and comparing the validation results. Our validation methodology offers a streamlined workflow to extract the “true” accuracy of a CFD solver.

CFD Simulation of Airflow Organization in the Ship Accommodation

2014 ◽  
Vol 711 ◽  
pp. 91-95
Author(s):  
Kun Zhang ◽  
Hai Xu Li ◽  
Jin Ling Wang
Keyword(s):  
Air Conditioning ◽  
High Performance ◽  
Cfd Simulation ◽  
Simulation Analysis ◽  
Fluid Dynamic ◽  
Temperature Fields ◽  
Design Stage ◽  
Air Conditioning System ◽  
Design And Optimization ◽  
Airflow Distribution

Efficient ventilation and sound air current are significant to improve indoor air quality (IAQ) and control the contamination concentration. Healthy and comfort air conditioning will provide a strong guarantee for high-performance work. While limited by lots of conditions, the airflow distribution in room is very difficult to be revealed, so numerical simulation and analysis for airflow organization become more and more important during the design stage of ventilation and air conditioning system. In the paper a ship accommodation is taken as a model to do simulation analysis on the effect of different airflow organizations. On the basis of computational fluid dynamic (CFD) theory and methodology, the temperature fields, velocity fields and air age fields under different airflow organizations are gotten by means of Airpak3.1. All these search works will be helpful for the further design and optimization for the ventilation and air conditioning system of the ship accommodation.

scholarly journals Analisis Perbedaan Mesh Pada Simulasi Boiler PLTGU Tanjung Priok Berbasis CFD

Jurnal METTEK ◽  
2020 ◽  
Vol 6 (1) ◽  
pp. 46
Author(s):  
I Nyoman Agus Adi Saputra ◽  
I Gusti Bagus Wijaya Kusuma ◽  
I Gusti Ngurah Priambadi
Keyword(s):  
Computational Fluid Dynamic ◽  
Cfd Simulation ◽  
Initial Conditions ◽  
Fluid Dynamic ◽  
Working Fluid ◽  
Process Stage ◽  
Convergence Study ◽  
Simulation Results ◽  
Gas Power Plant ◽  
Meshing Process

Penelitian Analisis Perbedaan Mesh berbasis Computational Fluid Dynamic (CFD) ini dilakukan Pada Boiler PLTGU Tanjung Priok. Boiler atau reboiler dalam sistem PLTGU dikategorikan sebagai alat penukar kalor karena perpindahan panasnya dilakukan tanpa kontak langsung antara media pemanas dengan media yang dipanaskan. Fluida kerja pada boiler PLTGU Tanjung Priok berupa gas methane dan air. Penelitian ini bertujuan melihat jumlah pembagian elemen terhadap hasil simulasi dengan menggunakan dua model Studi konvergensi grid yaitu dengan grid kasar, dan yang paling optimal melalui hasil simulasi CFD. Metode yang digunakan mulai dari mendesain geometri boiler sesuai kondisi di lapangan menginput initial conditions dan  boundry conditions. Data hasil penelitian yang sudah di lakukan pada simulasi boiler menunjukkan bahwa baik temperatur, tekanan dan kecepatan aliran memiliki nilai yang sama besar dan tidak di pengaruhi oleh pembagian elemen yang di lakukan pada saat proses meshing dari elemen yang paling kasar dengan jumlah total sebanyak 203.363 sampai pada tahap  proses meshing dengan elemen teroptimal yang berjumlah sebanyak 1.491.428 berdasarkan hal tersebut maka proses simulasi yang dilakukan menjadi lebih efisien karena proses perhitungan data dari elemen yang lebih sedikit mendapatkan hasil yang sama dengan elemen yang lebih banyak. The research on Mesh Difference Analysis based on Computational Fluid Dynamic (CFD) was conducted at Tanjung Priok PLTGU Boiler. Boilers or reboilers in PLTGU systems are categorized as heat exchangers because the heat transfer is done without direct contact between the heating media and the heated media. The working fluid in the Tanjung Priok gas power plant boiler is in the form of methane gas and water. This study aims to look at the number of elements divided against the simulation results by using two grid convergence study models, namely with a coarse grid, and the most optimal through CFD simulation results. The method used starts from designing the boiler geometry according to the field conditions, inputting initial conditions and boundry conditions. Data from research that has been done on boiler simulations shows that both temperature, pressure and flow velocity have the same value and are not affected by the division of elements carried out during the meshing process of the most coarse elements with a total number of 203.363 up to the meshing process stage with the optimum elements totaling 1,491,428 based on this, the simulation process carried out becomes more efficient because the process of calculating data from fewer elements gets the same results with more elements.

scholarly journals Hydrodynamic Analysis in Redesigning a Monohull Passenger Ship into a Catamaran

2021 ◽  
Vol 328 ◽  
pp. 07007
Author(s):  
Ivory Giyan Mitari ◽  
Wiwin Sulistyawati ◽  
Purwo Joko Suranto
Keyword(s):  
Fluid Dynamic ◽  
Resistance Coefficient ◽  
Cfd Analysis ◽  
Total Resistance ◽  
Hull Form ◽  
Hydrodynamic Analysis ◽  
Friction Resistance ◽  
Passenger Ship ◽  
Technological Developments ◽  
Primary Basis

In line with technological developments, many studies have led to the factors that consider hull shape planning. Therefore, innovations in hull form planning are the primary basis for obtaining a hull that is considered efficient in reducing ship resistance and fuel consumption. This study aims to modify the design of a monohull and transform it into a catamaran while maintaining the total length and Displacement ratio. The ship model used is the Monohull passenger ship with a rounded shape and modified to become a catamaran with a chine shape. The hull chine symmetrical was determined by stagger to the length ratio of S/L 0.3. The hydrodynamic investigations and calculations of models using Computational Fluid Dynamic (CFD). Analysis hydrodynamic on both hulls carried out on the components of total resistance, viscous resistance, friction resistance, and wave resistance with variations of Froude number: 0.3: 0.5: 0.7: 0.9 and 1.2. From the results of the analysis, it is found that the calculation of the coefficient of resistance on the catamaran with the Chine hull is smaller than the monohull. Fn 0.7 at S/L 0.3, the catamaran produces a resistance coefficient that is more favorable than the other speeds.

scholarly journals Numerical Simulation of a Rectangular Clarifier Using Drift-Flux Model in OpenFOAM

2021 ◽  
Author(s):  
Muritala Alade Amidu ◽  
Kamal Kayode AbdulRaheem
Keyword(s):  
Cfd Simulation ◽  
Fluid Dynamic ◽  
Design Stage ◽  
Operational Parameters ◽  
Mixture Flow ◽  
Water Particle ◽  
Drift Flux Model ◽  
Particle Mixture ◽  
Drift Flux ◽  
Flux Model

Abstract A computation fluid dynamic (CFD) simulation of a rectangular clarifier is performed in this study using a drift-flux model in OpenFOAM CFD code. Using this model with turbulence model, the key characteristics (re-circulation and sedimentation) of water-particle mixture flow in a rectangular clarifier are reasonably reproduced. A fairly good agreement is obtained between the simulation results and experimental data of the velocity profiles. Thus, with the demonstrated capability of this CFD model for the prediction of hydrodynamic and sedimentation behavior of water-particle mixture flow, several design issues such as the determination of the best location of baffle in a clarifier can be investigated and addressed. This method can not only provide general conceptual information at the initial design stage but can also be used to perform analysis of different configurations and the effect of changes in operational parameters.

Prediction of Surface Ship's Residual Resistance Coefficient Using Neural Networks

2013 ◽  
Vol 756-759 ◽  
pp. 3141-3144
Author(s):  
Li Hua Song ◽  
Zhi Guo Zhang ◽  
Xian Zhou Wang ◽  
Da Kui Feng
Keyword(s):  
Neural Network ◽  
Froude Number ◽  
Resistance Coefficient ◽  
Design Stage ◽  
Accurate Estimation ◽  
Target Variable ◽  
Residual Resistance ◽  
The Neural Network ◽  
The Relationship

The Holtrop method, which provides a prediction of the components of surface ships total resistance, is widely used at ships initial design stage for estimating the resistance. In this paper a neural network model which performs the same role as the Holtrop method is presented to predict the residual resistance. A multilayer perceptron has been trained with the data generated by the Holtrop method to learn the relationship between the input (length-displacement ratio, prismatic coefficient, breadth-draft ratio and Froude number) and the target variable (the residual resistance coefficient). The results of this model have been compared against those provided by the Holtrop method and it is found that the quality of the prediction is improved over the entire range of data. The neural network provides an accurate estimation of the residual resistance with the Froude number and the hull geometry coefficients as variables.

CFD and Neural Network-Based Predicting for Oil Delivery Performance of Oil Pump in Engines

2011 ◽  
Vol 230-232 ◽  
pp. 784-788
Author(s):  
Bao Hong Tong ◽  
Jun Yin ◽  
Yin Liu
Keyword(s):  
Neural Network ◽  
Cfd Simulation ◽  
Fluid Dynamic ◽  
Prediction Method ◽  
Operating Conditions ◽  
Ann Model ◽  
Delivery Performance ◽  
Oil Pump ◽  
Oil Flow ◽  
Simulation Results

Oil delivery pefromance of oil pump in engines are investigated by a new prediction method based on computational fluid dynamic (CFD) and artificial neural network (ANN). CFD analysis was done by using Fluent commercial code and distribution of velocity of pump’s internal flow field was achieved by the solving of pump’s CFD model. Infromation data about oil pump’s rotate speed, supplying pressure, oil temperature and oil flow rate were obtained by CFD simulation analyzing. ANN model that used to describe the delivery performance of oil pump was employed, and the model was trained by learning samples from those CFD simulation results. Predicting for the delivery performance of oil pump under various operating conditions were carried out by this model. Experimental results were also used to validate the obtained simulation results. The studies show that the ANN(trained by CFD learning samples) predictions are in very close agreement with the oil flow obtained experimentally or predicted by CFD. The method introduced here can give useful supports for optimization designing of oil pump’s dimension.

scholarly journals Effect of the Addition of Hydrofoil on Lift Force and Resistance in 60 M High-Speed Vessel

Kapal ◽  
2020 ◽  
Vol 17 (3) ◽  
pp. 95-106
Author(s):  
Izzuddin Nadzir Ismail ◽  
Parlindungan Manik ◽  
Mahendra Indiaryanto
Keyword(s):  
Froude Number ◽  
Computational Fluid Dynamic ◽  
High Speed ◽  
Lift Force ◽  
Fluid Dynamic ◽  
Model Analysis ◽  
Total Resistance ◽  
High Speeds ◽  
Sea Transportation ◽  
Resistance Value

The development of sea transportation technology is needed to meet the demand for ships that can carry heavier loads and operate at high speeds. Modifications in the form of additional hydrofoil variations were conducted to produce higher lift and reduce the resistance generated by the ship so that the ship can go more efficiently at high speed. This study aims to obtain the effect of adding hydrofoil to ships with variations in the type and shape of foil and find out which types and shapes can reduce resistance on the ship. This research was conducted with several model analysis tests using Computational Fluid Dynamic (CFD) based software, namely Tdyn, at several different speeds. The results of this study show that of the six variation models analyzed, rectangular fully submerged foil models can reduce the total resistance value of the ship by 17.822% from the original ship on Froude Number (Fr) 0.670. The type and shape of the foil is very influential on the lift and resistance produced by the ship.

scholarly journals Study Reduction of Resistance on The Flat Hull Ship of The Semi-Trimaran Model: Hull Vane Vs Stern Foil

CFD Letters ◽  
2021 ◽  
Vol 13 (12) ◽  
pp. 32-44
Author(s):  
Rahmat Azis Nabawi ◽  
Syahril ◽  
Primawati
Keyword(s):  
Froude Number ◽  
Cfd Simulation ◽  
Optimal Position ◽  
Ship Model ◽  
Resistance Reduction ◽  
Simulation Results

Flat hull ships is appraised for its superiority due to the manufacturing simplicity and lower investment costs, yet the ship has its own weakness for it requires a greater resistance. As a matter of fact, a significant reduction on the resistance can be done with foil installation but it is necessary to study the optimal position of the foil installation. This study is aimed at revealing the effectiveness of the Hull Vane and Stern Foil installation in reducing the resistance experienced by the flat hull ship of the semi-trimaran model. The research was conducted by comparing the resistance experienced by the flat hull ship of the semi-trimaran model without foil, Hull vane and Stern foil installations. In addition, the disclosure of resistance experienced by each ship model was carried out by using CFD simulation. The simulation results revealed that the installation of the Hull vane and Stern foil was able to reduce the resistance experienced by the flat hull ship of the semi-trimaran model. The largest reduction occurred in Froude number 1.1, where the Hull vane installation was able to reduce resistance by 12.44% and on the ship model with Stern foil installation the resistance reduction was 5.25%. Based on the results of this CFD simulation, it can be concluded that the Hull Vane installation is more optimal in reducing resistance on the flat hull ship of the semi-trimaran model.

Computational fluid dynamics aided optimisation of liquid state antiseptic injection to water networks

2014 ◽  
Vol 9 (3) ◽  
pp. 362-369
Author(s):  
Gábor Gönczi
Keyword(s):  
Cfd Simulation ◽  
Fluid Dynamic ◽  
Current Trend ◽  
Water Pipe ◽  
Cfd Modelling ◽  
Liquid Form ◽  
Additional Energy ◽  
Pipe Length ◽  
Static Mixers ◽  
Chlorine Gas

Waterworks mostly use chlorine as an antiseptic substance. It can be added in gaseous or liquid form. The simplest technique is to use gaseous injection but it carries the most risk as chlorine gas is highly toxic. Therefore, the current trend is to switch to the much safer hypo doser technology, whereby the hypo is injected into the water pipes with injector tubes, similarly to chlorination but the mixing of the antiseptic liquid is more problematic. Correct placement of the inlet and measurement points is indispensable. With the help of the computational fluid dynamic (CFD) simulation not only can the flow of the specific water pipe be modelled but also mixing of the antiseptic fluid can be modelled, thereby the measurement and inlet points can be installed at the optimal locations. In very short pipe sections with a limited amount of pipe length to achieve proper mixing the use of static mixers was suggested. Efficiency of the static mixers is variable and they increase the pressure loss on the specific water pipe section, which inflicts additional energy costs. With the help of CFD modelling, the fluid dynamic phenomena (vortices, backflows, etc.) on these pipe sections can be utilised to help mixing of the antiseptic substance meaning the use of static mixers can be avoided.

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