scholarly journals Micro- and Macro-Scale Measurement of Flow Velocity in Porous Media: A Shadow Imaging Approach for 2D and 3D

Optics ◽  
2020 ◽  
Vol 1 (1) ◽  
pp. 71-87 ◽  
Author(s):  
Reza Sabbagh ◽  
Mohammad Amin Kazemi ◽  
Hirad Soltani ◽  
David S. Nobes
Keyword(s):  
Porous Medium ◽  
Porous Media ◽  
Flow Pattern ◽  
Flow Measurement ◽  
Measurement Techniques ◽  
Three Dimensional ◽  
Two Dimensions ◽  
Detailed Knowledge ◽  
Micro Scale ◽  
Macro Scale

Flow measurement in porous media is a challenging subject, especially when it comes to performing a three-dimensional (3D) velocimetry at the micro scale. Volumetric flow measurement techniques such as defocusing and tomographic imaging generally involve rigorous procedures, complex experimental setups, and multi-part data processing procedures. However, detailed knowledge of the flow pattern at the pore and subpore scales is important in interpreting the phenomena that occur inside the porous media and understanding the macro-scale behaviors. In this work, the flow of an oil inside a porous medium is measured at the pore and subpore scales using refractive index matching (RIM) and shadowgraph imaging techniques. At the macro scale, flow is measured using the particle image velocimetry (PIV) method in two dimensions (2D) to confirm the volumetric nature of the flow and obtain the overall flow pattern in the vicinity of the flow entrance and at the far field. At the micro scale, the three-dimensional (3D) flow within an arbitrary volume of the porous medium was quantified using 2D particle-tracking velocimetry (PTV) utilizing the law of conservation of mass. Using the shadowgraphy method and a single camera makes the flow measurement much less complex than the approaches using laser light sheets or multiple cameras with multiple viewing angles.

The Three-Dimensional Surface Topographic Characterisation of Diamond Grinding Wheels

2010 ◽  
Vol 126-128 ◽  
pp. 690-695
Author(s):  
David Lee Butler
Keyword(s):  
Measurement Techniques ◽  
Three Dimensional ◽  
Surface Measurement ◽  
Grinding Wheel ◽  
Profile Measurement ◽  
Detailed Knowledge ◽  
Grinding Wheels ◽  
Diamond Grinding ◽  
Insight Into ◽  
Dimensional Surface

Surface measurement using three-dimensional stylus instruments is a relatively new technique that offers numerous advantages over more traditional profilometry methods. The information generated is, unlike profile measurement, less subjective and more statistical providing additional insight into the surface structure. One application of surface measurement that has encountered problems when using the profilometry method is that of grinding wheel characterisation. The wheel surface texture (topography) and the conditions under which it is generated have a profound effect upon the grinding performance as characterised by the grinding forces, power consumption, temperature, and surface integrity of components. A detailed knowledge of the nature of the topography of the grinding wheel would provide further insight into surface interactions between the wheel and workpiece as well as enabling improved control of the grinding process in general. In this paper four diamond grinding wheels of 91 and 181 micron grit size were subjected to differing dressing conditions to produce varying final wheel topographies. Three-dimensional surface measurement techniques were employed to quantitatively characterise the topographic change and provide an aerial estimation of the number of cutting grains. The results demonstrate that the techniques can distinguish between a worn and dressed wheel. In addition, the parametric values generated from the various surfaces can aid the user in determining when re-dressing is required.

scholarly journals On the Two-Scale Modelling of Elastohydrodynamic Lubrication in Tilted-Pad Bearings

Lubricants ◽  
2018 ◽  
Vol 6 (3) ◽  
pp. 78 ◽  
Author(s):  
Gregory de Boer ◽  
Andreas Almqvist
Keyword(s):  
Surface Topography ◽  
Load Capacity ◽  
Three Dimensional ◽  
Elastohydrodynamic Lubrication ◽  
Multiscale Methods ◽  
Operating Conditions ◽  
Real Surface ◽  
Micro Scale ◽  
Macro Scale ◽  
Heterogeneous Multiscale

A two-scale method for modelling the Elastohydrodynamic Lubrication (EHL) of tilted-pad bearings is derived and a range of solutions are presented. The method is developed from previous publications and is based on the Heterogeneous Multiscale Methods (HMM). It facilitates, by means of homogenization, incorporating the effects of surface topography in the analysis of tilted-pad bearings. New to this article is the investigation of three-dimensional bearings, including the effects of both ideal and real surface topographies, micro-cavitation, and the metamodeling procedure used in coupling the problem scales. Solutions for smooth bearing surfaces, and under pure hydrodynamic operating conditions, obtained with the present two-scale EHL model, demonstrate equivalence to those obtained from well-established homogenization methods. Solutions obtained for elastohydrodynamic operating conditions, show a dependency of the solution to the pad thickness and load capacity of the bearing. More precisely, the response for the real surface topography was found to be stiffer in comparison to the ideal. Micro-scale results demonstrate periodicity of the flow and surface topography and this is consistent with the requirements of the HMM. The means of selecting micro-scale simulations based on intermediate macro-scale solutions, in the metamodeling approach, was developed for larger dimensionality and subsequent calibration. An analysis of the present metamodeling approach indicates improved performance in comparison to previous studies.

scholarly journals Digital laser micro- and nanoprinting

Nanophotonics ◽  
2018 ◽  
Vol 8 (1) ◽  
pp. 27-44 ◽  
Author(s):  
Qingfeng Li ◽  
David Grojo ◽  
Anne-Patricia Alloncle ◽  
Boris Chichkov ◽  
Philippe Delaporte
Keyword(s):  
Three Dimensional ◽  
Digital Fabrication ◽  
Two Dimensions ◽  
Minimum Size ◽  
Direct Writing ◽  
3D Objects ◽  
Wide Range ◽  
Macro Scale ◽  
Forward Transfer ◽  
Pros And Cons

AbstractLaser direct writing is a well-established ablation technology for high-resolution patterning of surfaces, and since the development of additive manufacturing, laser processes have also appeared very attractive for the digital fabrication of three-dimensional (3D) objects at the macro-scale, from few millimeters to meters. On the other hand, laser-induced forward transfer (LIFT) has demonstrated its ability to print a wide range of materials and to build functional micro-devices. For many years, the minimum size of laser-printed pixels was few tens of micrometers and is usually organized in two dimensions. Recently, new approaches have been investigated, and the potential of LIFT technology for printing 2D and 3D sub-micrometer structures has become real. After a brief description of the LIFT process, this review presents the pros and cons of the different digital laser printing technologies in the aim of the additive nanomanufacturing application. The transfer of micro- and nano-dots in the liquid phase from a solid donor film appears to be the most promising approach to reach the goal of 3D nanofabrication, and the latest achievements obtained with this method are presented and discussed.

EVAPORATION OF A FLUID IN CAPILLARY POROUS MEDIA USING A 3D CORRELATED NETWORK MODEL

2006 ◽  
Vol 17 (12) ◽  
pp. 1763-1776 ◽  
Author(s):  
JÚLIO CÉSAR C B R MOREIRA ◽  
KRISHNASWAMY RAJAGOPAL
Keyword(s):  
Porous Medium ◽  
Porous Media ◽  
Network Model ◽  
Correlation Length ◽  
Phase Distribution ◽  
Three Dimensional ◽  
Direct Consequence ◽  
Size Distributions ◽  
Evaporation Process ◽  
Pore Size Distributions

We present the results from simulation studies of evaporation of a single fluid in a capillary porous medium. Employing a three-dimensional site-bond correlated network model to represent a porous medium, namely Clashac sandstone, we analyze different aspects of the phase distribution by evaporation of a single fluid in the porous medium. As a direct consequence of the porous medium utilized, we analyze the influence of a strongly disordered porous media with a broad range of pore and throat size distributions in the evaporation process. Experimental data togheter with throat and pore size distributions were used to build and match the network model, allowing us to determine the porosimetric curve for the Clashac sandstone for different degrees of correlation. Also, the correlation length was obtained from the percolation theory. In our case study the evaporation process modeled was insensitive to the different degrees of correlation that might occur between pores and throats. In addition, it was observed that the evaporation pattern was the same for all analyzed networks above the correlation length.

Instability of pressure-driven gas–liquid two-layer channel flows in two and three dimensions

2018 ◽  
Vol 849 ◽  
pp. 1-34 ◽  
Author(s):  
Lennon Ó Náraigh ◽  
Peter D. M. Spelt
Keyword(s):  
Flow Pattern ◽  
Linear Theory ◽  
Three Dimensional ◽  
Two Dimensions ◽  
Channel Flows ◽  
Three Dimensions ◽  
Nonlinear Behaviour ◽  
Two Dimensional ◽  
Vorticity Field ◽  
Flow Pattern Map

We study unstable waves in gas–liquid two-layer channel flows driven by a pressure gradient, under stable stratification, not assumed to be set in motion impulsively. The basis of the study is direct numerical simulation (DNS) of the two-phase Navier–Stokes equations in two and three dimensions for moderately large Reynolds numbers, accompanied by a theoretical description of the dynamics in the linear regime (Orr–Sommerfeld–Squire equations). The results are compared and contrasted across a range of density ratios $r=\unicode[STIX]{x1D70C}_{liquid}/\unicode[STIX]{x1D70C}_{gas}$. Linear theory indicates that the growth rate of small-amplitude interfacial disturbances generally decreases with increasing $r$; at the same time, the cutoff wavenumbers in both streamwise and spanwise directions increase, leading to an ever-increasing range of unstable wavenumbers, albeit with diminished growth rates. The analysis also demonstrates that the most dangerous mode is two-dimensional in all cases considered. The results of a comparison between the DNS and linear theory demonstrate a consistency between the two approaches: as such, the route to a three-dimensional flow pattern is direct in these cases, i.e. through the strong influence of the linear instability. We also characterize the nonlinear behaviour of the system, and we establish that the disturbance vorticity field in two-dimensional systems is consistent with a mechanism proposed previously by Hinch (J. Fluid Mech., vol. 144, 1984, p. 463) for weakly inertial flows. A flow-pattern map constructed from two-dimensional numerical simulations is used to describe the various flow regimes observed as a function of density ratio, Reynolds number and Weber number. Corresponding simulations in three dimensions confirm that the flow-pattern map can be used to infer the fate of the interface there also, and show strong three-dimensionality in cases that exhibit violent behaviour in two dimensions, or otherwise the development of behaviour that is nearly two-dimensional behaviour possibly with the formation of a capillary ridge. The three-dimensional vorticity field is also analysed, thereby demonstrating how streamwise vorticity arises from the growth of otherwise two-dimensional modes.

scholarly journals From micro-scale to macro-scale modeling of solute transport in drying capillary porous media

2021 ◽  
Vol 165 ◽  
pp. 120722
Author(s):  
Faeez Ahmad ◽  
Arman Rahimi ◽  
Evangelos Tsotsas ◽  
Marc Prat ◽  
Abdolreza Kharaghani
Keyword(s):  
Porous Media ◽  
Solute Transport ◽  
Micro Scale ◽  
Scale Modeling ◽  
Macro Scale

Multi-Scale Stereolithography Using Shaped Beams

2017 ◽  
Author(s):  
Huachao Mao ◽  
Yuen-Shan Leung ◽  
Yuanrui Li ◽  
Pan Hu ◽  
Wei Wu ◽  
...  
Keyword(s):  
Laser Beam ◽  
Tool Path ◽  
Three Dimensional ◽  
Laser Exposure ◽  
Micro Scale ◽  
Multi Scale ◽  
Good Surface ◽  
Single Scale ◽  
Macro Scale ◽  
Micro Patterns

Current Stereolithography (SL) can fabricate three-dimensional (3D) objects in a single scale level, e.g. printing macro-scale or micro-scale objects. However, it is difficult for the SL printers to fabricate a 3D macro-scale object with micro-scale features. In the paper a novel SL-based multi-scale fabrication method is presented to address such a problem. The developed SL process can fabricate multi-scale features by dynamically changing the shape and size of a laser beam. Different shaped beams are realized by switching apertures with different micro-patterns. The laser beam without using any micro-patterns is used to fabricate the macro-scale features, while the shaped laser beams with smaller sizes are used to fabricate micro-patterned features. Accordingly, the tool path planning method for the multi-scale fabrication process are developed so that macro-scale and micro-scale features can be built by using different layer thicknesses, laser exposure time, and scanning paths. Compared with the conventional SL process based on a fixed laser beam size, our process can fabricate multi-scale features in a 3D object. It also has fast fabrication speed and good surface quality.

High Rayleigh number convection in a three-dimensional porous medium

2014 ◽  
Vol 748 ◽  
pp. 879-895 ◽  
Author(s):  
Duncan R. Hewitt ◽  
Jerome A. Neufeld ◽  
John R. Lister
Keyword(s):  
Porous Medium ◽  
Three Dimensional ◽  
Field Measurements ◽  
Two Dimensions ◽  
Dimensional Scaling ◽  
Dynamical Flow ◽  
Background Temperature ◽  
Relationship Of ◽  
Rayleigh Numbers ◽  
Steady Convection

AbstractHigh-resolution numerical simulations of statistically steady convection in a three-dimensional porous medium are presented for Rayleigh numbers $Ra \leqslant 2 \times 10^4$. Measurements of the Nusselt number $Nu$ in the range $1750 \leqslant Ra \leqslant 2 \times 10^4$ are well fitted by a relationship of the form $Nu = \alpha _3 Ra + \beta _3$, for $\alpha _3 = 9.6 \times 10^{-3}$ and $\beta _3 = 4.6$. This fit indicates that the classical linear scaling $Nu \sim Ra$ is attained, and that $Nu$ is asymptotically approximately $40\, \%$ larger than in two dimensions. The dynamical flow structure in the range $1750 \leqslant Ra \leqslant 2\times 10^4$ is analysed, and the interior of the flow is found to be increasingly well described as $Ra \to \infty $ by a heat-exchanger model, which describes steady interleaving columnar flow with horizontal wavenumber $k$ and a linear background temperature field. Measurements of the interior wavenumber are approximately fitted by $k\sim Ra^{0.52 \pm 0.05}$, which is distinguishably stronger than the two-dimensional scaling of $k\sim Ra^{0.4}$.

Scaled Fluid-Flow Models with Geometry Differing from that of Prototype

1972 ◽  
Vol 12 (03) ◽  
pp. 220-228 ◽  
Author(s):  
F. van Daalen ◽  
H.R. van Domselaar
Keyword(s):  
Porous Medium ◽  
Porous Media ◽  
Three Dimensional ◽  
Flow Models ◽  
Oil Flow ◽  
Homogeneous Models ◽  
Length Width ◽  
Three Dimensional Models ◽  
Scaled Models ◽  
Similarity Groups

Abstract Experiments on oil displacement from homogeneous porous media have shown that the component porous media have shown that the component oil flow across the layer is often negligibly small compared with that parallel to it. This result is applied in the inspectional analysis of the equations governing the macroscopic displacement processes. It is shown that in rectangular homogeneous models the dimensionless groups l/h and a can usually be neglected. This finding has been proved experimentally in rectangular models of various dimensions, two extremes of which are described in this paper. The work has been extended to curved models. An additional requirement is that the angles of dip must be small. Comparative experiments have been carried out in three-dimensional models of various geometrical configurations. The results of both studies indicate a greater flexibility in the use of models than has previously been assumed. Introduction The production behavior of petroleum reservoirs can to a large extent be investigated with the help of scaled models, although the great number of parameters to be scaled in such processes precludes parameters to be scaled in such processes precludes complete simulation. However, not all parameters have an equally important influence on the process; and it is therefore necessary to select the most important ones and investigate which parameters can possibly be neglected. To date, oil reservoirs have almost always been represented by models of similar geometry. In other words, the characteristic length, width and height are scaled down by the same factor. For many reservoirs, however, the length-height ratio is extremely large, and laboratory models become inconveniently long or very thin. In such cases it would be desirable to make the model too thick relatively. It will be demonstrated that this is in a number of cases a justifiable solution. DERIVATION OF THE SIMILARITY GROUPS IN SCALING RECTANGULAR MODELS For the purpose of this paper, it is sufficient to derive the similarity groups for the displacement of oil by water in a homogeneous, isotropic, porous medium where the reservoir pressure is roughly maintained; thus an incompressible flow can be simulated. For more complex cases the scaling rules can be derived in a way similar to that given here. The following equations apply to the simultaneous flow of two incompressible fluids such as oil and water in a two-dimensional porous medium (see Fig. 1). We distinguish here two regions in which either water or oil flows, the regions being separated by a transition zone. (1) ox u  = (2) oy u  = (3) wx u  = (4) wy u  = JPT P. 220

scholarly journals Three-dimensional laser printing of macro-scale glass objects at a micro-scale resolution

2020 ◽  
Author(s):  
Peng Wang ◽  
Wei Chu ◽  
Xiaolong Li ◽  
Zijie Lin ◽  
Jian Xu ◽  
...  
Keyword(s):  
Three Dimensional ◽  
Micro Scale ◽  
Laser Printing ◽  
Macro Scale
Sign in / Sign up

Export Citation Format

Share Document