scholarly journals Nearby boundaries create eddies near microscopic filter feeders

2009 ◽  
Vol 7 (46) ◽  
pp. 851-862 ◽  
Author(s):  
Rachel E. Pepper ◽  
Marcus Roper ◽  
Sangjin Ryu ◽  
Paul Matsudaira ◽  
Howard A. Stone
Keyword(s):  
Three Dimensional ◽  
Pond Water ◽  
Filter Feeder ◽  
Dimensional Finite Element ◽  
Flow Approximation ◽  
The Common ◽  
Filter Feeders ◽  
Three Dimensional Finite Element ◽  
Approximate Equations ◽  
Good Agreement

We show through calculations, simulations and experiments that the eddies often observed near sessile filter feeders are frequently due to the presence of nearby boundaries. We model the common filter feeder Vorticella , which is approximately 50 µm across and which feeds by removing bacteria from ocean or pond water that it draws towards itself. We use both an analytical stokeslet model and a Brinkman flow approximation that exploits the narrow-gap geometry to predict the size of the eddy caused by two parallel no-slip boundaries that represent the slides between which experimental observations are often made. We also use three-dimensional finite-element simulations to fully solve for the flow around a model Vorticella and analyse the influence of multiple nearby boundaries. Additionally, we track particles around live feeding Vorticella in order to determine the experimental flow field. Our models are in good agreement both with each other and with experiments. We also provide approximate equations to predict the experimental eddy sizes owing to boundaries both for the case of a filter feeder between two slides and for the case of a filter feeder attached to a perpendicular surface between two slides.

Heat Transfer in Grinding-Hardening of a Cylindrical Component

2011 ◽  
Vol 325 ◽  
pp. 35-41 ◽  
Author(s):  
Thai Nguyen ◽  
Liang Chi Zhang ◽  
Da Le Sun
Keyword(s):  
Heat Transfer ◽  
Three Dimensional ◽  
Hardened Layer ◽  
Transfer Model ◽  
Plunge Grinding ◽  
Cylindrical Component ◽  
Dimensional Finite Element ◽  
Three Dimensional Finite Element ◽  
Grinding Hardening ◽  
Good Agreement

A three-dimensional finite element heat transfer model incorporating a moving heat source was developed to investigate the heat transfer mechanism in grinding-hardening of a cylindrical component. The model was applied to analyze the grinding-hardening of quenchable steel 1045 by two grinding methods, traverse and plunge grinding. It was found that the heat generated can promote the martensitic phase transformation in the ground workpiece. As a result, a hardened layer with a uniform thickness can be produced by traverse grinding. However, the layer thickness generated by plunge grinding varies circumferentially. The results are in good agreement with the experimental observations.

Residual Stress Prediction for Non-Axisymmetric Vessel Penetration Welds

2008 ◽  
Author(s):  
Kazuo Ogawa ◽  
Nobuyoshi Yanagida ◽  
Koichi Saito
Keyword(s):  
Residual Stress ◽  
Finite Element ◽  
Three Dimensional ◽  
Measurement Data ◽  
Fe Model ◽  
Stress Distributions ◽  
Dimensional Finite Element ◽  
Stress Prediction ◽  
Three Dimensional Finite Element ◽  
Good Agreement

Residual stress distribution in an oblique nozzle jointed to a vessel with J-groove welds was analyzed using a three-dimensional finite element method. All welding passes were considered in a 180-degree finite element (FE) model with symmetry. Temperature and stress were modeled for simultaneous bead laying. To determine residual stress distributions at the welds experimentally, a mock-up specimen was manufactured. The analytical results show good agreement with the experimental measurement data, indicating that FE modeling is valid.

scholarly journals Analysis of deformation and microstructure evolution during the cogging process of Waspaloy alloy

2019 ◽  
Vol 254 ◽  
pp. 02008
Author(s):  
Marcin Kukuryk ◽  
Jerzy Winczek ◽  
Marek Gucwa
Keyword(s):  
Dynamic Recrystallization ◽  
Effective Strain ◽  
Three Dimensional ◽  
Work Piece ◽  
Commercial Program ◽  
Dimensional Finite Element ◽  
Three Dimensional Finite Element ◽  
Evolution Of Microstructure ◽  
Deform 3D ◽  
Good Agreement

The hot deformation behavior of Waspaloy alloy has been investigated by two-pass hot cogging process. The paper presents theoretical end experimental analysis of deformations and microstructural evolutions. The results of a thermo-mechanical simulation for the spatial hot cogging process on the shaped anvils with the application of the three–dimensional finite element method, are presented. The numerical calculation gave an assessment of the effective strain, mean stress and temperature distributions in the work-piece. Models for predicting the evolution of microstructure were developed for dynamic recrystallization and grain growth phenomena. The influence of shape of the anvils on the grain size after dynamic recrystallization was analyzed. The numerical analysis was performed using a commercial program "DEFORM 3D" with thermo-mechanical and microstructural evolution coupled. The results are compared with the experimental data, a good agreement between the predicted and experimental results was obtained.

Dynamic Analysis and Three-Dimensional Finite Element Simulation of Cracked Gear

2007 ◽  
Vol 353-358 ◽  
pp. 1072-1077 ◽  
Author(s):  
Ren Ping Shao ◽  
Xin Na Huang ◽  
Pu Rong Jia ◽  
Wan Lin Guo ◽  
Kaoru Hirota
Keyword(s):  
Fault Diagnosis ◽  
Gear Tooth ◽  
Three Dimensional ◽  
Dynamic Features ◽  
Cracked Beam ◽  
Element Simulation ◽  
Dimensional Finite Element ◽  
Simulation Results ◽  
Three Dimensional Finite Element ◽  
Good Agreement

A method of damage detection and fault diagnosis for gears is presented based on the theory of elastomeric dynamics according to the theory of cracked beam. It takes an advantage of accurate fault diagnosis of gear body using the change of dynamic features and has some advantages for dynamic design of gear systems.The dynamics characteristics, i.e., natural frequency, vibration shape,dynamic response and so on, due to crack of gear tooth are studied, and the gear dynamics characteristics caused by the position and size of crack are deeply investigated by comparison with FEM. The theoretical analysis results are contrasted with numerical simulation results and shows good agreement with the result by FEM. The proposed method can be used to detect damage and diagnose fault for gear structures and also can be applied to designing dynamic characteristics for gear systems.

Finite Element Model of a Heated Wire Catalyst in Cross Flow

2008 ◽  
Author(s):  
Katie Leichliter ◽  
Bob Lounsbury ◽  
Judi Steciak ◽  
Ralph Budwig ◽  
Steve Beyerlein
Keyword(s):  
Finite Element ◽  
Three Dimensional ◽  
Cross Flow ◽  
Element Model ◽  
Trailing Edges ◽  
Dimensional Finite Element ◽  
Fuel Mixtures ◽  
Three Dimensional Finite Element ◽  
Calculated Average ◽  
Good Agreement

Experimentally obtained temperatures of a heated coiled platinum wire in low Reynolds Number cross-flow were compared with a three-dimensional finite element (finite volume) model. The calculated average wire temperature was in good agreement with experimentally obtained values with deviations close to experimental uncertainty bounds at temperatures between 530K and 815K. The model predicted a temperature variation along each coil, with the lowest temperatures along the leading edges of the coil and the higher temperatures at the trailing edges. The rate of heat generated at the wire surface from catalytic reactions was found for the ignition of lean propane/oxygen/nitrogen mixtures. We studied the coiled catalytic wire as part of our efforts to ignite very lean homogeneous air-fuel mixtures in transportation engines under conditions approaching Homogeneous Charge Compression Ignition (HCCI).

Three-Dimensional Finite Element Analysis on Open-Die Block Forging Design

1992 ◽  
Vol 114 (4) ◽  
pp. 459-464 ◽  
Author(s):  
Chinghua Hung ◽  
Shiro Kobayashi
Keyword(s):  
Finite Element ◽  
Three Dimensional ◽  
Rigid Plastic ◽  
Flat Bottom ◽  
Element Analysis ◽  
Dimensional Finite Element ◽  
Die Set ◽  
Cylindrical Workpiece ◽  
Three Dimensional Finite Element ◽  
Good Agreement

Three-dimensional rigid-plastic finite element method was used to analyze the practice of open-die block forging, focusing on the effects of die configurations and forging pass designs. Four combinations of die configurations were investigated: conventional flat dies, top flat/bottom V-shaped dies, and double V-shaped dies with 120 and 135 deg included angles. Two different pass designs, 90 and 180 deg rotation angles between succeeding passes, were applied to each die set. The results include the magnitude and distribution of effective strains along the center line of the cylindrical workpiece and the final shape of the workpiece. Good agreement was observed in comparison with experimental data from physical modeling method, and several suggestions were made for choosing suitable dies.

Fatigue Behavior and Deformation of Aluminum and Steel HVOF Sprayed with WC-Co Coatings

1997 ◽  
Author(s):  
A. Ibrahim ◽  
C.C. Berndt
Keyword(s):  
Fatigue Life ◽  
Room Temperature ◽  
Fatigue Behavior ◽  
Three Dimensional ◽  
Element Model ◽  
Fatigue Tests ◽  
Dimensional Finite Element ◽  
Life Distributions ◽  
Three Dimensional Finite Element ◽  
Good Agreement

Abstract The effect of WC-Co coating on the high cycle fatigue (HCF) behavior of SAE 12L14 steel and 2024-T4 aluminum was investigated. The fatigue tests were performed at room temperature and 370°C. The fatigue life distributions of specimens in the polished, grit blasted, peened, and coated conditions are presented as a function of the probability of failure. HVOF sprayed WC-Co coating has influenced the fatigue life of aluminum and steel. Factors contributing to this influence, which include grit blasting, elastic modulus, and residual stress, are discussed. A three-dimensional finite-element model (FEM) of the coated specimen was used to calculate the stress distribution across the coating and the substrate. The results of the analytical model are in good agreement with fatigue lives observed experimentally.

Stress analysis of cylindrical shells with nozzles due to external run pipe moments

2000 ◽  
Vol 35 (3) ◽  
pp. 159-170 ◽  
Author(s):  
M. D Xue ◽  
H. H Wang ◽  
K. C Hwang
Keyword(s):  
Thin Shell ◽  
Cylindrical Shells ◽  
Large Diameter ◽  
Three Dimensional ◽  
Diameter Ratio ◽  
Test Results ◽  
Present Solution ◽  
Dimensional Finite Element ◽  
Three Dimensional Finite Element ◽  
Good Agreement

In this paper the analytical results of two normally intersecting cylindrical shells subjected to external moments on the ends of main shells are presented. The thin shell theoretical solutions are obtained on the basis of the modified Morley equation for the main shell with a cut out with large diameter ratio and of the Goldenveizer equation for the branch tube with a nonplaner end. The results are in good agreement with the previous test results and with Moffat's three-dimensional finite element method results. The design curves based on the present solution can be applied to d/D ≤ 0.8 successfully.

Experimental and numerical study of process-induced total spring-in of corner-shaped composite parts

2016 ◽  
Vol 51 (16) ◽  
pp. 2347-2361 ◽  
Author(s):  
K Furkan Çiçek ◽  
Merve Erdal ◽  
Altan Kayran
Keyword(s):  
Numerical Model ◽  
Numerical Study ◽  
Three Dimensional ◽  
Interaction Mechanism ◽  
Element Model ◽  
Shape Design ◽  
Optical Scanning ◽  
Dimensional Finite Element ◽  
Three Dimensional Finite Element ◽  
Good Agreement

Process-induced total spring-in of corner-shaped composite parts manufactured via autoclave-forming technique using unidirectional prepreg is studied both numerically and experimentally. In the numerical study, a three-dimensional finite element model which takes into account the cure shrinkage of the resin, anisotropic material properties of the composite part and the tool-part interaction is developed. The outcome of the numerical model is verified experimentally. For this purpose, U-shaped composite parts are manufactured via autoclave-forming technique. Process-induced total spring-in, due to the combined effect of material anisotropy and tool-part interaction, at different sections of the U-shaped parts are measured with use of the combination of the three-dimensional optical scanning technique and the generative shape design. Total spring-in determined by the numerical model is found to be in good agreement with the average total spring-in measured experimentally. The effect of tool-part interaction mechanism on the total spring-in is studied separately to ascertain its effect on the total spring-in behavior clearly. It is shown that with the proper modeling of the tool-part interaction, numerically determined total spring-in approaches the experimentally determined total spring-in.

Three-Dimensional Finite-Element Modelling of Deformation in Weld-Based Rapid Prototyping

2006 ◽  
Vol 220 (6) ◽  
pp. 875-885 ◽  
Author(s):  
M P Mughal ◽  
H Fawad ◽  
R A Mufti
Keyword(s):  
Experimental Data ◽  
Residual Stress ◽  
Finite Element ◽  
Gas Metal Arc Welding ◽  
Three Dimensional ◽  
Single Layer ◽  
Mechanical Analysis ◽  
Dimensional Finite Element ◽  
Three Dimensional Finite Element ◽  
Good Agreement

Residual stress-induced deformations are a major cause of tolerance loss in solid freeform fabrication process employing direct metal deposition. In this article, a three-dimensional finite-element (FE) thermo-mechanical model is presented to predict the residual stress-induced deformations with application to processes where material is added using a distributed moving heat source, e.g. gas metal arc welding (GMAW). A sequentially coupled thermo-mechanical analysis is performed simulating buildup of a single layer on a bolted rectangular substrate. The material used in the present study is mild steel, with temperature-dependent material properties and the material modelled as elastic perfectly plastic. The numerical results are compared with experimental data by manufacturing plate-shaped single-layered specimen, using an indigenously developed semi-automatic deposition system. The fusion zone and temperatures predicted by numerical model show good agreement with experimental data, and the deformations of the substrate in bolted and unbolted conditions are also in good agreement. It has been observed that the heat transfer conditions vary during deposition; therefore, any assumption of thermal symmetry is not valid. Thermal cycling during deposition is the main cause of deformations. The effect of bolting is also very important.

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