Translational Added Mass of Axisymmetric Underwater Vehicles with Forward Speed Using Computational Fluid Dynamics

2011 ◽  
Vol 55 (03) ◽  
pp. 185-195
Author(s):  
Virag Mishra ◽  
S. Vengadesan
Keyword(s):  
Fluid Dynamics ◽  
Computational Fluid Dynamics ◽  
Cross Flow ◽  
Added Mass ◽  
Navier Stokes ◽  
Inertia Force ◽  
Mass Coefficient ◽  
Computational Fluid Dynamics Cfd ◽  
Accelerated Flow ◽  
Axisymmetric Bodies

This paper presents a computational fluid dynamics (CFD) approach to the calculation of translational added mass coefficient of axisymmetric underwater bodies in both longitudinal and transverse directions. The proposed method involves CFD simulations of accelerated as well as uniform flows past axisymmetric bodies based on Reynolds averaged Navier-Stokes (RANS) equations and makes use of the results of these simulations to obtain the inertia force acting on a body as a function of time. The translational added mass can be obtained from this inertia force history. Validation of the methodology is presented for the benchmark case of accelerated flow past sphere and infinitely long circular cylinder in cross-flow for which analytical solutions of the added mass problem are well known.

scholarly journals Experimental Validation Data for Computational Fluid Dynamics of Forced Convection on a Vertical Flat Plate

2015 ◽  
Vol 138 (1) ◽  
Author(s):  
Jeff R. Harris ◽  
Blake W. Lance ◽  
Barton L. Smith
Keyword(s):  
Fluid Dynamics ◽  
Computational Fluid Dynamics ◽  
Forced Convection ◽  
Vertical Plate ◽  
Navier Stokes ◽  
Validation Dataset ◽  
System Response ◽  
Cfd Validation ◽  
Validation Data ◽  
Computational Fluid Dynamics Cfd

A computational fluid dynamics (CFD) validation dataset for turbulent forced convection on a vertical plate is presented. The design of the apparatus is based on recent validation literature and provides a means to simultaneously measure boundary conditions (BCs) and system response quantities (SRQs). All important inflow quantities for Reynolds-Averaged Navier-Stokes (RANS). CFD are also measured. Data are acquired at two heating conditions and cover the range 40,000 < Rex < 300,000, 357 <  Reδ2 < 813, and 0.02 < Gr/Re2 < 0.232.

Development of SIMPLE-Like Algorithms for Incompressible Navier-Stokes Equations in Liquid Processing of Materials

2012 ◽  
Vol 184-185 ◽  
pp. 944-948 ◽  
Author(s):  
Hai Jun Gong ◽  
Yang Liu ◽  
Xue Yi Fan ◽  
Da Ming Xu
Keyword(s):  
Fluid Dynamics ◽  
Computational Fluid Dynamics ◽  
Stokes Equations ◽  
Simple Algorithm ◽  
Navier Stokes ◽  
Incompressible Fluid Flow ◽  
Numerical Accuracy ◽  
Simple Scheme ◽  
Navier Stokes Equations ◽  
Computational Fluid Dynamics Cfd

For a clear and comprehensive opinion on segregated SIMPLE algorithm in the area of computational fluid dynamics (CFD) during liquid processing of materials, the most significant developments on the SIMPLE algorithm and its variants are briefly reviewed. Subsequently, some important advances during last 30 years serving as increasing numerical accuracy, enhancing robustness and improving efficiency for Navier–Stokes (N-S) equations of incompressible fluid flow are summarized. And then a so-called Direct-SIMPLE scheme proposed by the authors of present paper introduced, which is different from SIMPLE-like schemes, no iterative computations are needed to achieve the final pressure and velocity corrections. Based on the facts cited in present paper, it conclude that the SIMPLE algorithm and its variants will continue to evolve aimed at convergence and accuracy of solution by improving and combining various methods with different grid techniques, and all the algorithms mentioned above will enjoy widespread use in the future.

Comparison of four types of membrane bioreactor systems in terms of shear stress over the membrane surface using computational fluid dynamics

2013 ◽  
Vol 68 (12) ◽  
pp. 2534-2544 ◽  
Author(s):  
N. Ratkovich ◽  
T. R. Bentzen
Keyword(s):  
Fluid Dynamics ◽  
Computational Fluid Dynamics ◽  
Membrane Fouling ◽  
Two Phase Flow ◽  
Membrane Surface ◽  
Cross Flow ◽  
Membrane Bioreactors ◽  
Phase Flow ◽  
Two Phase ◽  
Computational Fluid Dynamics Cfd

Membrane bioreactors (MBRs) have been used successfully in biological wastewater treatment to solve the perennial problem of effective solids–liquid separation. A common problem with MBR systems is clogging of the modules and fouling of the membrane, resulting in frequent cleaning and replacement, which makes the system less appealing for full-scale applications. It has been widely demonstrated that the filtration performances in MBRs can be greatly improved with a two-phase flow (sludge–air) or higher liquid cross-flow velocities. However, the optimization process of these systems is complex and requires knowledge of the membrane fouling, hydrodynamics and biokinetics. Modern tools such as computational fluid dynamics (CFD) can be used to diagnose and understand the two-phase flow in an MBR. Four cases of different MBR configurations are presented in this work, using CFD as a tool to develop and optimize these systems.

Numerical Prediction of Blended Wing Body Aerodynamic Characteristics at Subsonic Speed

2014 ◽  
Vol 71 (2) ◽  
Author(s):  
Pang Jung Hoe ◽  
Nik Ahmad Ridhwan Nik Mohd
Keyword(s):  
Fluid Dynamics ◽  
Computational Fluid Dynamics ◽  
High Performance ◽  
Aerodynamic Characteristic ◽  
Aerodynamic Characteristics ◽  
Numerical Prediction ◽  
Navier Stokes ◽  
Subsonic Speed ◽  
Computational Fluid Dynamics Cfd ◽  
Blended Wing Body

The need for high performance and green aircraft has brought the blended wing (BWB) aircraft concept to the centre of interest for many researchers. BWB is a type of aircraft characterized by a complex blending geometry between fuselage and wing. Recently, many researches had been performed to unlock its aerodynamic complexity that is still not well understood. In this paper, aerodynamic characteristic of a baseline BWB configuration derived from simple conventional aircraft configuration was analysed using the Reynolds-averaged Navier-Stokes computational fluid dynamics (CFD) solver. The main objectives of this work are to predict the aerodynamic characteristics of the BWB concept at steady flight conditions and at various pitch angles. The results obtained are then compared against a simple conventional aircraft configuration (CAC). The results show that the BWB configuration used has 24% higher L/D ratio than the CAC. The increment to the L/D however is mainly due to lower drag than the improvement in the lift. 

Computational Fluid Dynamics–Computational Structural Dynamics Rotor Coupling Using an Unstructured Reynolds-Averaged Navier–Stokes Methodology

2012 ◽  
Vol 57 (1) ◽  
pp. 1-14 ◽  
Author(s):  
Jennifer N. Abras ◽  
C. Eric Lynch ◽  
Marilyn J. Smith
Keyword(s):  
Fluid Dynamics ◽  
Computational Fluid Dynamics ◽  
Structural Dynamics ◽  
Flight Test ◽  
Navier Stokes ◽  
Structured Grid ◽  
Direct Contrast ◽  
Computational Structural Dynamics ◽  
Computational Fluid Dynamics Cfd ◽  
Grid Points

The focus of this paper is to discuss the unique challenges introduced through the use of unstructured grids in rotorcraft computational fluid dynamics (CFD)–computational structural dynamics (CSD) coupling. The use of unstructured grid methodology in CFD has been expanding because of the advantages in grid generation and modeling of complex configurations. However, the resulting amorphous distribution of the grid points on the rotor blade surface provides no information with regard to the orientation of the blade, in direct contrast to structured grid methodology that can take advantage of the ordered mapping of points to identify the orientation as well as simplifying airloads integration. A methodology has been developed and is described here, which now permits unstructured methods to be utilized for elastic rotary-wing simulations. This methodology is evaluated through comparison of the UH60A rotor with available flight test data for forward flight.

Virtual Model Basin for Resistance, Maneuvering, and Seakeeping: A RANS CFD Based Approach

2007 ◽  
Author(s):  
Balasubramanyam Sasanapuri ◽  
Viraj Suresh Shirodkar ◽  
Wesley Wilson ◽  
Samir Kadam ◽  
Shin Hyung Rhee
Keyword(s):  
Fluid Dynamics ◽  
Computational Fluid Dynamics ◽  
Free Surface ◽  
Water Resistance ◽  
Primary Objective ◽  
Navier Stokes ◽  
Theory Method ◽  
Virtual Model ◽  
Calm Water ◽  
Computational Fluid Dynamics Cfd

A Virtual Model Basin (VMB) is developed based on a Computational Fluid Dynamics (CFD) approach to solving the Reynolds Averaged Navier-Stokes (RANS) equations along with the Volume of Fluid (VOF) method for predicting the free surface. The primary objective of this work is to develop methodologies for the VMB and to demonstrate the capabilities for a generic multi-hull ship geometry. The VMB is used to simulate various model basin tests for steady resistance, maneuvering and seakeeping. For a generic catamaran hull configuration, the methodologies are used for solving these problems and the results are discussed in this paper. VMB results are compared with the results of a benchmarked potential flow theory method for calm water resistance.

Computational Fluid Dynamics (CFD) Simulation of Cross-flow Mode Operation of Membrane for Downstream Processing

2019 ◽  
Vol 13 (1) ◽  
pp. 57-68 ◽  
Author(s):  
Anirban Banik ◽  
Tarun Kanti Bandyopadhyay ◽  
Sushant Kumar Biswal
Keyword(s):  
Fluid Dynamics ◽  
Computational Fluid Dynamics ◽  
Membrane Filtration ◽  
Cfd Simulation ◽  
Cross Flow ◽  
Flow Mode ◽  
Computational Fluid Dynamics Cfd ◽  
The Cross ◽  
Fluent 6.3

Background: Membrane filtration process produced good quality of permeate flux due to which it is used in different industries like dairy, pharmaceutical, sugar, starch and sweetener industry, bioseparation, purification of biomedical materials, and downstream polishing etc. The cross-flow mode of operation has also been used to improve the quality of the Rubber Industrial effluent of Tripura, India. </P><P> Method: The Computational Fluid Dynamics (CFD) simulation of the cross-flow membrane is done by using ANSYS Fluent 6.3. The meshing of the geometry of the membrane is done by Gambit 2.4.6 and a grid size of 100674, the number of faces is 151651 and number of nodes being 50978 has been selected for the simulation purpose from the grid independence test. We have revised and included all patents in the manuscripts related to the membrane filtration unit. </P><P> Results: Single phase Pressure-Velocity coupled Simple Algorithm and laminar model is used for the simulation of the developed model and Fluent 6.3 used for the prediction of pressure, pressure drop, flow phenomena, wall shear stress and shear strain rate inside the module is studied for cross flow membrane. </P><P> Conclusion: From the study, it has been found that CFD simulated results hold good agreement with the experimental values.

Richardson Extrapolation-Based Discretization Uncertainty Estimation for Computational Fluid Dynamics

2014 ◽  
Vol 136 (12) ◽  
Author(s):  
Tyrone S. Phillips ◽  
Christopher J. Roy
Keyword(s):  
Fluid Dynamics ◽  
Computational Fluid Dynamics ◽  
Convergence Rates ◽  
Richardson Extrapolation ◽  
Local Solution ◽  
Navier Stokes ◽  
Grid Convergence ◽  
Computational Fluid Dynamics Cfd ◽  
Grid Convergence Index ◽  
2D And 3D

This study investigates the accuracy of various Richardson extrapolation-based discretization error and uncertainty estimators for problems in computational fluid dynamics (CFD). Richardson extrapolation uses two solutions on systematically refined grids to estimate the exact solution to the partial differential equations (PDEs) and is accurate only in the asymptotic range (i.e., when the grids are sufficiently fine). The uncertainty estimators investigated are variations of the grid convergence index and include a globally averaged observed order of accuracy, the factor of safety method, the correction factor method, and least-squares methods. Several 2D and 3D applications to the Euler, Navier–Stokes, and Reynolds-Averaged Navier–Stokes (RANS) with exact solutions and a 2D turbulent flat plate with a numerical benchmark are used to evaluate the uncertainty estimators. Local solution quantities (e.g., density, velocity, and pressure) have much slower grid convergence on coarser meshes than global quantities, resulting in nonasymptotic solutions and inaccurate Richardson extrapolation error estimates; however, an uncertainty estimate may still be required. The uncertainty estimators are applied to local solution quantities to evaluate accuracy for all possible types of convergence rates. Extensions were added where necessary for treatment of cases where the local convergence rate is oscillatory or divergent. The conservativeness and effectivity of the discretization uncertainty estimators are used to assess the relative merits of the different approaches.

The Application of Computational Fluid Dynamics to Railway Aerodynamics

1993 ◽  
Vol 207 (2) ◽  
pp. 133-141 ◽  
Author(s):  
A P Gaylard
Keyword(s):  
Fluid Dynamics ◽  
Computational Fluid Dynamics ◽  
High Speed ◽  
Cross Flow ◽  
Practical Application ◽  
High Speed Rail ◽  
Promising Strategy ◽  
Temperature Environment ◽  
Computational Work ◽  
Computational Fluid Dynamics Cfd

The growing application of computational fluid dynamics (CFD) to railway aerodynamics is described. After cautioning against overselling the capabilities of CFD codes, a review is presented of the more significant computational work undertaken in this field. Three recent applications of CFD are examined: (a) a high-speed rail vehicle in a cross-wind; (b) cross-flow impingement on a freight vehicle in the Channel Tunnel; (c) the temperature environment in a stationary passenger train. Comparative experimental data are offered for each of the above. An analysis of these applications is used to derive a promising strategy for the practical application of CFD.

scholarly journals VERIFICATION OF SCHRENK METHOD FOR WING LOADING ANALYSIS OF SMALL UNMANNED AIRCRAFT USING NAVIERSTOKES BASED CFD SIMULATION

2018 ◽  
Vol 15 (2) ◽  
pp. 161 ◽  
Author(s):  
Arifin Rasyadi Soemaryanto ◽  
Nurhayyan Halim Rosid
Keyword(s):  
Fluid Dynamics ◽  
Computational Fluid Dynamics ◽  
Approximation Method ◽  
Cfd Simulation ◽  
Unmanned Aircraft ◽  
Navier Stokes ◽  
Aerodynamic Load ◽  
Wing Loading ◽  
Computational Fluid Dynamics Cfd ◽  
Cfd Method

Prediction of an aerodynamic load acting on a wing or usually called wing loading becomes an important stage for structural analysis. Several methods have been used in estimating the wing loading. Schrenk approximation method is commonly used to achieve the fast estimation of lift distribution along wingspan, but in order to achieve a high level accuracy of aerodynamic prediction, computational fluid dynamics (CFD) with Navier Stokes-based equation can be used. LAPAN Surveillance UAV (LSU series) has been chosen to represent an aerodynamics analysis on generic small unmanned aircraft with twinboom vertical stabilizer configuration. This study was focused to verify the Schrenk approximation method using high accuracy numerical simulation (CFD). The goal of this study was to determine the lift distribution along wingspan and a number of errors between Schrenk approximation and CFD method. In this study, Schrenk approximation result showed similarity with the CFX simulation. So the two results have been verified in analysis of wing loading. ABSTRAKPrediksi dari beban aerodinamika yang terjadi pada sayap menjadi salah satu tahap yang penting dalam analisis struktur perancangan pesawat. Beberapa metode telah digunakan untuk mengestimasi besarnya beban aerodinamika pada sayap. Metode Schrenk umum digunakan untuk estimasi cepat perhitungan besar distribusi gaya angkat di sepanjang sayap. Guna mencapai tingkat akurasi yang tinggi dari prediksi aerodinamika, simulasi Computational Fluid Dynamics (CFD) dengan berbasis persamaan Navier-Stokes dapat digunakan. Pesawat nirawak LSU dipilih untuk merepresentasikan analisis aerodinamika pada pesawat nirawak dengan konfigurasi twin-tailboom pusher. Fokus dari studi yang dilakukan adalah untuk memverifikasi dari metode pendekatan dari Schrenk dengan menggunakan metode yang memiliki akurasi tinggi seperti simulasi CFD. Tujuan dari studi adalah untuk menghitung distribusi gaya angkat sepanjang sayap dan menentukan seberapa besar error dari kedua metode.

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