A comparison of analytical and numerical model predictions of shallow soil temperature variation with experimental measurements

The capability of using Focused Ion Beam (FIB) for milling microchannels is experimentally and theoretically investigated. Microchannel structures are fabricated by a NanoFab 150 FIB machine, using an Arsenic (As2+) ion source. A beam current of 5 pA at 90 keV accelerating energy is used. Several microchannel patternings are milled at various dwell times at pixel spacing of 14.5 nm on top of a 60 nm gold-coated silicon wafer. An analytical/numerical model is developed to predict the FIB milling behavior. By comparing with the experimental measurements, the model predictions have been demonstrated to be reliable for guiding and controlling the milling processes.

Download Full-text

Non-Linear Numerical Model Predictions of Flow Over an Isolated Hill of Moderate Slope

Boundary-Layer Meteorology ◽

10.1023/a:1000944817965 ◽

1998 ◽

Vol 87 (3) ◽

pp. 381-408 ◽

Cited By ~ 13

Author(s):

F.E. Hewer

Keyword(s):

Numerical Model ◽

Model Predictions ◽

Non Linear

Download Full-text

Analytical Model to Predict Nonhomogeneous Soil Temperature Variation

Journal of Solar Energy Engineering ◽

10.1115/1.2870823 ◽

1995 ◽

Vol 117 (2) ◽

pp. 100-107 ◽

Cited By ~ 7

Author(s):

M. Krarti ◽

D. E. Claridge ◽

J. F. Kreider

Keyword(s):

Thermal Properties ◽

Soil Temperature ◽

Temperature Variation ◽

Analytical Model ◽

Soil Surface ◽

Deep Soil ◽

Soil Thermal Properties ◽

Order Of Magnitude ◽

Soil Surface Temperature ◽

Annual Time

This paper presents an analytical model to predict the temperature variation within a multilayered soil. The soil surface temperature is assumed to have a sinusoidal time variation for both daily and annual time scales. The soil thermal properties in each layer are assumed to be uniform. The model is applied to two-layered, three-layered, and to nonhomogeneous soils. In case of two-layered soil, a detailed analysis of the thermal behavior of each layer is presented. It was found that as long as the order of magnitude of the thermal diffusivity of soil surface does not exceed three times that of deep soil; the soil temperature variation with depth can be predicted accurately by a simplified model that assumes that the soil has constant thermal properties.

Download Full-text

A combined model for pseudo-rapidity distributions in Cu–Cu collisions at BNL-RHIC energies

International Journal of Modern Physics E ◽

10.1142/s0218301316500257 ◽

2016 ◽

Vol 25 (04) ◽

pp. 1650025 ◽

Cited By ~ 2

Author(s):

Z. J. Jiang ◽

J. Wang ◽

Y. Huang

Keyword(s):

Experimental Data ◽

Proper Time ◽

Charged Particles ◽

Dense Matter ◽

Rapidity Distribution ◽

Experimental Measurements ◽

Combined Model ◽

Model Predictions ◽

Phobos Collaboration ◽

Rapidity Distributions

The charged particles produced in nucleus–nucleus collisions come from leading particles and those frozen out from the hot and dense matter created in collisions. The leading particles are conventionally supposed having Gaussian rapidity distributions normalized to the number of participants. The hot and dense matter is assumed to expand according to the unified hydrodynamics, a hydro model which unifies the features of Landau and Hwa–Bjorken model, and freeze out into charged particles from a time-like hypersurface with a proper time of [Formula: see text]. The rapidity distribution of this part of charged particles can be derived analytically. The combined contribution from both leading particles and unified hydrodynamics is then compared against the experimental data performed by BNL-RHIC-PHOBOS Collaboration in different centrality Cu–Cu collisions at [Formula: see text] and 62.4[Formula: see text]GeV, respectively. The model predictions are consistent with experimental measurements.

Download Full-text

Comparison of Four Friction Models: Feature Prediction

Journal of Computational and Nonlinear Dynamics ◽

10.1115/1.4031768 ◽

2015 ◽

Vol 11 (3) ◽

Cited By ~ 5

Author(s):

Yun-Hsiang Sun ◽

Tao Chen ◽

Christine Qiong Wu ◽

Cyrus Shafai

Keyword(s):

Numerical Model ◽

Viscous Friction ◽

Friction Model ◽

Dynamic Features ◽

Numerical Predictions ◽

Wide Range ◽

Model Predictions ◽

Friction Models ◽

Parameter Identifications ◽

Model Structures

In this paper, we provide not only key knowledge for friction model selection among candidate models but also experimental friction features compared with numerical predictions reproduced by the candidate models. A motor-driven one-dimensional sliding block has been designed and fabricated in our lab to carry out a wide range of control tasks for the friction feature demonstrations and the parameter identifications of the candidate models. Besides the well-known static features such as break-away force and viscous friction, our setup experimentally demonstrates subtle dynamic features that characterize the physical behavior. The candidate models coupled with correct parameters experimentally obtained from our setup are taken to simulate the features of interest. The first part of this work briefly introduces the candidate friction models, the friction features of interest, and our experimental approach. The second part of this work is dedicated to the comparisons between the experimental features and the numerical model predictions. The discrepancies between the experimental features and the numerical model predictions help researchers to judge the accuracy of the models. The relation between the candidate model structures and their numerical friction feature predictions is investigated and discussed. A table that summarizes how to select the most optimal friction model among a variety of engineering applications is presented at the end of this paper. Such comprehensive comparisons have not been reported in previous literature.

Download Full-text

Multifidelity Recursive Cokriging for Dynamic Systems' Response Modification

Journal of Vibration and Acoustics ◽

10.1115/1.4040597 ◽

2018 ◽

Vol 141 (1) ◽

Author(s):

Luigi Bregant ◽

Lucia Parussini ◽

Valentino Pediroda

Keyword(s):

Numerical Model ◽

Numerical Simulations ◽

Dynamic Systems ◽

System Optimization ◽

The Other ◽

Experimental Measurements ◽

Reciprocal Influence ◽

Tests And Measurements ◽

Invaluable Tool ◽

Mixed Approach

In order to perform the accurate tuning of a machine and improve its performance to the requested tasks, the knowledge of the reciprocal influence among the system's parameters is of paramount importance to achieve the sought result with minimum effort and time. Numerical simulations are an invaluable tool to carry out the system optimization, but modeling limitations restrict the capabilities of this approach. On the other side, real tests and measurements are lengthy, expensive, and not always feasible. This is the reason why a mixed approach is presented in this work. The combination, through recursive cokriging, of low-fidelity, yet extensive, numerical model results, together with a limited number of highly accurate experimental measurements, allows to understand the dynamics of the machine in an extended and accurate way. The results of a controllable experiment are presented and the advantages and drawbacks of the proposed approach are also discussed.

Download Full-text

Thermal Cycling Simulation during Remelting Process of the Steel ASTM A743-CA6NM

Advanced Materials Research ◽

10.4028/www.scientific.net/amr.1082.100 ◽

2014 ◽

Vol 1082 ◽

pp. 100-105

Author(s):

Camila Almeida Martins ◽

Jhon Jairo Ramirez-Behainne

Keyword(s):

Numerical Model ◽

Thermal Cycling ◽

Material Properties ◽

Three Dimensional ◽

Fusion Line ◽

Maximum Deviation ◽

Experimental Measurements ◽

Ansys Fluent ◽

Simplifying Assumptions ◽

Volume Method

This study aimed to model numerically the thermal cycling resulting from the steel ASTM A743-CA6NM remelting process. The problem was solved with the support of the commercial software ANSYS / FLUENT ® 14.5 for the three-dimensional case using the finite volume method. The following simplifying assumptions were adopted: heat loss by natural convection, absence of radiation, no phase change, concentrated heat source, and thermophysical properties independent of temperature. The results were analyzed for two different current intensities: 90A and 130A, and compared with experimental measurements. The peak temperatures of the thermocouples near the fusion line for the current of 130A were well represented by the numerical model, with a maximum deviation of 9.62%. In the case of the more remote thermocouples from the fusion line, the best results were obtained for the current of 90A, not exceeding 5% of deviation. In general, it was found that the tested body is heated faster than in simulations. This can be considered as a consequence of the simplification in material properties, which were assumed constants with temperature. The results of this study demonstrate that, given the adopted simplifications, the numerical model was able to satisfactorily reproduce the experimentally measured thermal cycles.

Download Full-text

Solidification Heat Transfer and Base Separation Analysis in the Casting of an Energetic Material in a Projectile

Heat Transfer, Part B ◽

10.1115/imece2005-80432 ◽

2005 ◽

Cited By ~ 3

Author(s):

Dawei Sun ◽

S. Ravi Annapragada ◽

Suresh V. Garimella ◽

Sanjeev Sing

Keyword(s):

Heat Transfer ◽

Finite Element ◽

Numerical Model ◽

Residual Stresses ◽

Energetic Materials ◽

Energetic Material ◽

Complex Geometries ◽

Experimental Measurements ◽

Linear Temperature ◽

High Prandtl Number

This paper investigates the problem of base separation in the casting of energetic materials in a projectile. Special challenges that arise in casting high Prandtl number energetic materials in projectiles of complex geometries are addressed. A comprehensive numerical model is developed by integrating finite volume and finite element methods to analyze the thermal and flow fields as well as the residual stresses. The predictions, which are confirmed by experimental measurements, suggest that sustenance of a linear temperature profile along the projectile axis can eliminate base separation, and also reduce residual stresses in the final casting.

Download Full-text