On the Two-Dimensional Simplification of Three-Dimensional Cementless Hip Stem Numerical Models

2017 ◽  
Vol 139 (3) ◽  
Author(s):  
Fernando J. Quevedo González ◽  
Michael Reimeringer ◽  
Natalia Nuño
Keyword(s):  
Cortical Thickness ◽  
Variable Thickness ◽  
3D Model ◽  
Numerical Models ◽  
Computational Cost ◽  
Three Dimensional ◽  
Symmetry Plane ◽  
Stair Climbing ◽  
Side Plate ◽  
2D Model

Three-dimensional (3D) finite element (FE) models are commonly used to analyze the mechanical behavior of the bone under different conditions (i.e., before and after arthroplasty). They can provide detailed information but they are numerically expensive and this limits their use in cases where large or numerous simulations are required. On the other hand, 2D models show less computational cost, but the precision of results depends on the approach used for the simplification. Two main questions arise: Are the 3D results adequately represented by a 2D section of the model? Which approach should be used to build a 2D model that provides reliable results compared to the 3D model? In this paper, we first evaluate if the stem symmetry plane used for generating the 2D models of bone-implant systems adequately represents the results of the full 3D model for stair climbing activity. Then, we explore three different approaches that have been used in the past for creating 2D models: (1) without side-plate (WOSP), (2) with variable thickness side-plate and constant cortical thickness (SPCT), and (3) with variable thickness side-plate and variable cortical thickness (SPVT). From the different approaches investigated, a 2D model including a side-plate best represents the results obtained with the full 3D model with much less computational cost. The side-plate needs to have variable thickness, while the cortical bone thickness can be kept constant.

scholarly journals A comparison of a two-dimensional depth averaged flow model and a three-dimensional RANS model for predicting tsunami inundation and fluid forces

2018 ◽  
Author(s):  
Xinsheng Qin ◽  
Michael Motley ◽  
Randall LeVeque ◽  
Frank Gonzalez ◽  
Kaspar Mueller
Keyword(s):  
Built Environment ◽  
3D Model ◽  
Computational Cost ◽  
Three Dimensional ◽  
Vertical Direction ◽  
3D Models ◽  
Tsunami Inundation ◽  
Model Based ◽  
Fine Mesh ◽  
2D Model

Abstract. The numerical modeling of tsunami inundation that incorporates the built environment of coastal communities is challenging for both depth-integrated 2D and 3D models, not only in modeling the flow, but also in predicting forces on coastal structures. For depth-integrated 2D models, inundation and flooding in this region can be very complex with variation in the vertical direction caused by wave breaking on shore and interactions with the built environment and the model may not be able to produce enough detail. For 3D models, a very fine mesh is required to properly capture the physics, dramatically increasing the computational cost and rendering impractical the modeling of some problems. In this paper, comparisons are made between GeoClaw, a depth-integrated 2D model based on the nonlinear shallow water equations (NSWE), and OpenFOAM, a 3D model based on Reynolds Averaged Navier-Stokes (RANS) equation for tsunami inundation modeling. The two models were first validated against existing experimental data of a bore impinging onto a single square column. Then they were used to simulate tsunami inundation of a physical model of Seaside, Oregon. The resulting flow parameters from the models are compared and discussed, and these results are used to extrapolate tsunami-induced force predictions. It was found that the 2D model did not accurately capture the important details of the flow near initial impact due to the transiency and large vertical variation of the flow. Tuning the drag coefficient of the 2D model worked well to predict tsunami forces on structures in simple cases but this approach was not always reliable in complicated cases. The 3D model was able to capture transient characteristic of the flow, but at a much higher computational cost; it was found this cost can be alleviated by subdividing the region into reasonably sized subdomains without loss of accuracy in critical regions.

scholarly journals Mathematical Modelling for Micropiles Embedded in Salt Rock

2016 ◽  
Vol 12 (1) ◽  
pp. 23-35
Author(s):  
Georgiana Rădan (Toader) ◽  
Nicoleta Rădulescu ◽  
Gheorghe Oancea
Keyword(s):  
Mathematical Modelling ◽  
3D Model ◽  
Three Dimensional ◽  
Salt Rock ◽  
In Situ Tests ◽  
Calibration And Validation ◽  
Plaxis 3D ◽  
2D Model ◽  
Computing Models

Abstract This study presents the results of the mathematical modelling for the micropiles foundation of an investement objective located in Slanic, Prahova county. Three computing models were created and analyzed with software, based on Finite Element Method. With Plaxis 2D model was analyzed the isolated micropile and the three-dimensional analysis was made with Plaxis 3D model, for group of micropiles. For the micropiles foundation was used Midas GTS-NX model. The mathematical models were calibrated based with the in-situ tests results for axially loaded micropiles, embedded in salt rock. The paper presents the results obtained with the three software, the calibration and validation models.

Fetal weight estimation by automated three-dimensional limb volume model in late third trimester compared to two-dimensional model: a cross-sectional prospective observational study

2021 ◽  
Author(s):  
Xining Wu ◽  
Zihan Niu ◽  
Zhonghui Xu ◽  
Yuxin Jiang ◽  
Yixiu Zhang ◽  
...  
Keyword(s):  
Birth Weight ◽  
3D Model ◽  
Three Dimensional ◽  
Fetal Weight ◽  
Percentage Error ◽  
Limb Volume ◽  
Third Trimester ◽  
Volume Model ◽  
Estimated Error ◽  
2D Model

Abstract Background: Accurate estimation of fetal weight is important for prenatal care and for detection of fetal growth abnormalities. Prediction of fetal weight entails the indirect measurement of fetal biometry by ultrasound that is then introduced into formulae to calculate the estimated fetal weight. The aim of our study was to evaluate the accuracy of the automated three-dimensional(3D) fractional limb volume model to predict fetal weight in the third trimester.Methods: Prospective 2D and 3D ultrasonography were performed among women with singleton pregnancies 7 days before delivery to obtain 2D data, including fetal biparietal diameter, abdominal circumference and femur length, as well as 3D data, including the fractional arm volume (AVol) and fractional thigh volume (TVol). The fetal weight was estimated using the 2D model and the 3D fractional limb volume model respectively. Percentage error = (estimated fetal weight - actual birth weight) ÷ actual birth weight × 100. Systematic errors (accuracy) were evaluated as the mean percentage error (MPE). Random errors (precision) were calculated as±1 SD of percentage error.Results: Ultrasound examination was performed on 56 fetuses at 39.6 ± 1.4 weeks gestation. The average birth weight of the newborns was 3393 ± 530 g. The average fetal weight estimated by the 2D model was 3478 ± 467 g, and the MPE was 3.2 ± 8.9. The average fetal weights estimated by AVol and TVol of the 3D model were 3268 ± 467 g and 3250 ± 485 g, respectively, and the MPEs were -3.3 ± 6.6 and -3.9 ± 6.1, respectively. For the 3D TVol model, the proportion of fetuses with estimated error ≤ 5% was significantly higher than that of the 2D model (55.4% vs. 33.9%, p < 0.05). For fetuses with a birth weight < 3500 g, the accuracy of the AVol and TVol models were better than the 2D model (-0.8 vs. 7.0 and -2.8 vs. 7.0, both p < 0.05). Moreover, for these fetus, the proportions of estimated error ≤ 5% of the AVol and TVol models were 58.1% and 64.5%, respectively, significantly higher than that of the 2D model (19.4%) (both p < 0.05). The consistency of different examiners measuring fetal AVol and TVol were satisfactory,with the intraclass correlation coefficients of 0.921 and 0.963, respectively.Conclusion: In this cohort,the automated 3D fractional limb volume model improves the accuracy of weight estimation in most third-trimester fetuses. In particular, the 3D model estimation accuracy for fetuses with weight < 3500 g is significantly higher than that of the traditional 2D model.

scholarly journals Influence of Electric Field Coupling Model on the Simulated Performances of a GaN Based Planar Nanodevice

2013 ◽  
Vol 2013 ◽  
pp. 1-7 ◽  
Author(s):  
K. Y. Xu ◽  
Z. N. Wang ◽  
Y. N. Wang ◽  
J. W. Xiong ◽  
G. Wang
Keyword(s):  
Electric Field ◽  
3D Model ◽  
Second Harmonic ◽  
Strong Electric Field ◽  
Three Dimensional ◽  
Harmonic Oscillation ◽  
Two Dimensional ◽  
Dc Bias ◽  
Simulation Results ◽  
2D Model

The performances of a two-dimensional electron gas (2DEG) based planar nanodevice are studied by a two-dimensional-three-dimensional (2D-3D) combined model and an entirely 2D model. In both models, 2DEGs are depicted by 2D ensemble Monte Carlo (EMC) method. However electric field distributions in the devices are obtained by self-consistently solving 2D and 3D Poisson equations for the 2D model and the 2D-3D model, respectively. Simulation results obtained by both models are almost the same at low bias while showing distinguished differences at high bias. The 2D model predicts larger output current and slightly higher threshold voltage of Gunn oscillations. Although the fundamental frequencies of current oscillations obtained by both models are similar, the deviation of wave shape from sinusoidal waveform obtained by the 2D model is more serious than that obtained by 2D-3D model. Moreover, results obtained by the 2D model are more sensitive both to the bias conditions and to the change of device parameters. Interestingly, a look-like second harmonic oscillation has been observed at DC bias. We contribute the origin of divergences in simulation results to the different coupling path of electric field in the two models. And the second-harmonic oscillations at DC bias should be the result of the appearance of concomitant oscillations beside the channel excited by strong electric-field effects.

Comparison of Two-Dimensional and Three-Dimensional Thermal Models of the LENS® Process

2008 ◽  
Vol 130 (10) ◽  
Author(s):  
H. Yin ◽  
L. Wang ◽  
S. D. Felicelli
Keyword(s):  
Thermal Behavior ◽  
Molten Pool ◽  
3D Model ◽  
Dynamic Control ◽  
Three Dimensional ◽  
Element Model ◽  
Two Dimensional ◽  
3D Effects ◽  
Net Shaping ◽  
2D Model

A new two-dimensional (2D) transient finite element model was developed to study the thermal behavior during the multilayer deposition by the laser engineered net shaping rapid fabrication process. The reliability of the 2D model was evaluated by comparing the results obtained from the 2D model with those computed by a previously developed three-dimensional (3D) model. It is found that the predicted temperature distributions and the cooling rates in the molten pool and its surrounding area agree well with the experiment data available in literature and with the previous results calculated with the 3D model. It is also concluded that, for the geometry analyzed in this study, the 2D model can be used with good accuracy, instead of the computationally much more expensive 3D model, if certain precautions are taken to compensate for the 3D effects of the substrate. In particular, a 2D model could be applied to an in situ calculation of the thermal behavior of the deposited part during the fabrication, allowing dynamic control of the process. The 2D model is also applied to study the effects of substrate size and idle time on the thermal field and size of the molten pool.

Two-dimensional and three-dimensional numerical simulations of cycloidal propellers in hover

2016 ◽  
Vol 232 (7) ◽  
pp. 1223-1234
Author(s):  
Hu Yu ◽  
Zhang Hai Lang ◽  
Wang Geng Qi
Keyword(s):  
3D Model ◽  
Aerodynamic Force ◽  
Numerical Models ◽  
Leading Edge ◽  
Azimuth Angle ◽  
Dynamic Stall ◽  
Aerodynamic Forces ◽  
Vortex Interactions ◽  
Blade Model ◽  
2D Model

The cycloidal propellers for micro aerial vehicle scale cyclocopter in hovering status were studied in this paper based on the URANs solver using 2D, 2.5D, 3D half blade and 3D full blade model. The results from all numerical models were validated with the experimental results. It was found that 2.5D model cannot produce more accurate results than 2D model, hence results from 2D model were employed to discuss cycloidal rotor with infinite blade span. It was also indicated that the 3D half blade model produced the same results as 3D full blade model, but was more efficient than 3D model. The numerical simulation results of cycloidal rotor with finite (3D model) and infinite span (2D model) were compared. The results indicated that for the 2D cycloidal rotor with large blade pitching amplitude, there were leading edge and trailing edge vortices due to dynamic stall, which resulted in parallel blade vortex interactions. The parallel blade vortex interactions will also induce the fluctuation of aerodynamic forces. For the 3D blade with small aspect ratio, the flow was dominated by 3D dynamic stall and blade vortex interactions. The 3D flow due to finite blade span resulted in smooth dynamic stall and can weaken the parallel blade vortex interactions induced by dynamic stall vortices, hence no strong aerodynamic force fluctuation was observed. The perpendicular blade vortex interactions caused by blade tip vortices can induce cross flow when the azimuth angle of the rotor is between 270° and 360°, which reduces the strength of downwash in the region where the rotor azimuth angle is between 180° and 360°. This results in much smaller side force. Although sometimes the time-averaged aerodynamic forces obtained by 2D and 3D model were quite close to each other, the physics lying behind is quite different. Hence, it was not correct to use the 2D models to discuss the principles of cycloidal rotors with finite blade span.

scholarly journals Numerical Simulation of Three-Dimensional Dendrite Movement Based on the CA–LBM Method

Crystals ◽  
2021 ◽  
Vol 11 (9) ◽  
pp. 1056
Author(s):  
Qi Wang ◽  
Yingming Wang ◽  
Shijie Zhang ◽  
Binxu Guo ◽  
Chenyu Li ◽  
...  
Keyword(s):  
3D Model ◽  
Three Dimensional ◽  
Solidification Process ◽  
Movement Direction ◽  
Liquid Boundary ◽  
Alloy Microstructure ◽  
The Difference ◽  
Boltzmann Method ◽  
Solid Liquid ◽  
2D Model

At present, the calculation of three-dimensional (3D) dendrite motion using the cellular automata (CA) method is still in its infancy. In this paper, a 3D dendrite motion model is constructed. The heat, mass, and momentum transfer process in the solidification process of the alloy melt are calculated using a 3D Lattice–Boltzmann method (LBM). The growth process for the alloy microstructure is calculated using the CA method. The interactions between dendrites and the melt are assessed using the Ladd method. The solid–liquid boundary of the solute field in the movement process is assessed using the solute extrapolation method. The translational velocity of the equiaxed crystals in motion is calculated using the classical mechanical law. The rationality of the model is verified and the movement of single and multiple 3D equiaxed crystals is simulated. Additionally, the difference between 3D dendrite movement and two-dimensional (2D) dendrite movement is analyzed. The results demonstrate that the growth of moving dendrites is asymmetric. The growth velocity and falling velocity of the dendrite in the 3D model are faster than that in 2D model, while the simulation result is more realistic than that of the 2D model. When multiple dendrites move, the movement direction of the dendrites will change due to the merging of flow fields and other factors.

A Kriging-Based Surrogate Model for Seismic Fragility Analysis of Unanchored Storage Tanks

2019 ◽  
Author(s):  
Hoang Nam Phan ◽  
Fabrizio Paolacci ◽  
Daniele Corritore ◽  
Nicola Tondini ◽  
Oreste S. Bursi
Keyword(s):  
Surrogate Model ◽  
Seismic Vulnerability ◽  
Numerical Models ◽  
Fragility Curves ◽  
Computational Cost ◽  
Three Dimensional ◽  
Shaking Table ◽  
Fe Model ◽  
Storage Tanks ◽  
Damage State

Abstract The seismic vulnerability of aboveground steel storage tanks has been dramatically proved during the latest seismic events, which demonstrates the need for reliable numerical models for vulnerability and risk assessments of storage facilities. While for anchored aboveground tanks, simplified models are nowadays available and mostly used for the seismic vulnerability assessment, in the case of unanchored tanks, the scientific community is still working on numerical models capable of reliably predicting the nonlinearity due to uplift and sliding mechanisms. In this paper, a surrogate model based on a Kriging approach is proposed for a case study of an unanchored tank, whose calibration is performed on a three-dimensional finite element (3D FE) model using a reliable design of experiments (DOE) method. The verification of the 3D FE model is also done through a shaking table campaign. The outcomes show the effectiveness of the proposed model to build fragility curves at a low computational cost of the critical damage state of the tank, i.e., the plastic rotation of the shell-to-bottom joint.

Numerical Model for Shallow Wake behind Cylinder

2012 ◽  
Vol 212-213 ◽  
pp. 1205-1212
Author(s):  
Ling Li ◽  
Zhi Feng Yan ◽  
Zhao Wei Liu
Keyword(s):  
Shallow Water Equations ◽  
3D Model ◽  
Transverse Velocity ◽  
Longitudinal Velocity ◽  
Three Dimensional ◽  
Navier Stokes ◽  
Wake Structure ◽  
Wake Patterns ◽  
2D Shallow Water Equations ◽  
2D Model

Shallow wake patterns are investigated by numerical method based on the solutions of two-dimensional (2D) shallow water equations and three-dimensional (3D) Reynolds-Averaged Navier-Stokes (RANS) equations with the implicit scheme on collocated mesh in the FVM framework. The analysis are made on vorticity contour distribution, transverse velocity (uy) variation with time, Strouhal number (St) and time-averaged longitudinal velocity (ux) to verify the characteristics of shallow wakes behind cylinder. We compare the numerical results with Chen’s experiment very well and show the capability and difference of 2D model and 3D model in modeling shallow wake structure. The results show that the 2D model predicts the vortex street (VS) wake well, yet the 3D model is fit for the steady bubble (SB) wake. The 2D model performs more accurately when VS wake transforms to unsteady bubble (UB) wake, while the 3D model is better when UB wake transforms to SB wake.

scholarly journals Direct 3D model extraction method for color volume images

2021 ◽  
Vol 29 ◽  
pp. 133-140
Author(s):  
Bin Liu ◽  
Shujun Liu ◽  
Guanning Shang ◽  
Yanjie Chen ◽  
Qifeng Wang ◽  
...  
Keyword(s):  
3D Model ◽  
Clinical Medicine ◽  
Three Dimensional ◽  
Laplacian Matrix ◽  
Segmentation Method ◽  
Human Organs ◽  
Model Segmentation ◽  
Treatment Objective ◽  
Organ Models ◽  
Different Parts

BACKGROUND: There is a great demand for the extraction of organ models from three-dimensional (3D) medical images in clinical medicine diagnosis and treatment. OBJECTIVE: We aimed to aid doctors in seeing the real shape of human organs more clearly and vividly. METHODS: The method uses the minimum eigenvectors of Laplacian matrix to automatically calculate a group of basic matting components that can properly define the volume image. These matting components can then be used to build foreground images with the help of a few user marks. RESULTS: We propose a direct 3D model segmentation method for volume images. This is a process of extracting foreground objects from volume images and estimating the opacity of the voxels covered by the objects. CONCLUSIONS: The results of segmentation experiments on different parts of human body prove the applicability of this method.

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