A Lattice-Based Cellular Automata Modeling Approach for Granular Flow Lubrication

2005 ◽  
Vol 128 (2) ◽  
pp. 358-364 ◽  
Author(s):  
Venkata K. Jasti ◽  
C. Fred Higgs
Keyword(s):  
Cellular Automata ◽  
Granular Flow ◽  
Solid Lubricant ◽  
Granular Flows ◽  
Complex Flows ◽  
The Past ◽  
Modeling Approach ◽  
Ca Model ◽  
Model Benchmark ◽  
Good Agreement

Liquid lubricants break down at extreme temperatures and promote stiction in micro-/nanoscale environments. Consequently, using flows of solid granular particles as a “dry” lubrication mechanism in sliding contacts was proposed because of their ability to carry loads and accommodate surface velocities. Granular flows are highly complex flows that in many ways act similar to fluids, yet are difficult to predict because they are not well understood. Granular flows are composed of discrete particles that display liquid and solid lubricant behavior with time. This work describes the usefulness of employing lattice-based cellular automata (CA), a deterministic rule-based mathematics approach, as a tool for modeling granular flows in tribological contacts. In the past work, granular flows have been modeled using the granular kinetic lubrication (GKL) continuum modeling approach. While the CA modeling approach is constructed entirely from rules, results are in good agreement with results from the GKL model benchmark results. Velocity results of the CA model capture the well-known slip behavior of granular flows near boundaries. Solid fraction results capture the well-known granular flow characteristic of a highly concentrated center region. CA results for slip versus roughness also agree with GKL theory.

Granular Flow Lubrication: A Lattice-Based Cellular Automata Modeling Approach

2005 ◽  
Author(s):  
V. K. Jasti ◽  
C. F. Higgs
Keyword(s):  
Cellular Automata ◽  
Granular Flow ◽  
Solid Lubricant ◽  
Granular Flows ◽  
Complex Flows ◽  
Shear Cell ◽  
Modeling Approach ◽  
Ca Model ◽  
Model Benchmark ◽  
Good Agreement

Liquid lubricants break down at extreme temperatures and promote stiction in micro/nano-scale environments. Consequently, using flows of solid granular particles as a “dry” lubrication mechanism in sliding contacts was proposed, because of their ability to carry loads and accommodate surface velocities. Granular flows are highly complex flows that in many ways act similar to fluids, yet are difficult to predict because they are not well understood. Granular flows are composed of discrete particles which display fluid and solid lubricant behavior with time. This work describes the usefulness of employing lattice-based cellular automata (CA) as a tool for modeling granular flows in tribological contacts. The granular kinetic lubrication (GKL) continuum modeling approach has been successful at predicting trends gleaned from experiments conducted with granules in a couette shear cell. These results are used as a benchmark for determining the effectiveness of the CA modeling results. While the CA model was constructed entirely from rule-based mathematics, velocity and solid fraction results from the simulations were in good agreement with those from the GKL model benchmark results.

Using a Lattice-Based Cellular Automata Approach to Model the Load Carrying Capacity of Granular Flows

2007 ◽  
Author(s):  
Venkata K. Jasti ◽  
C. Fred Higgs
Keyword(s):  
Cellular Automata ◽  
Carrying Capacity ◽  
Extreme Temperature ◽  
Granular Flows ◽  
Load Carrying Capacity ◽  
Local Flow ◽  
The Past ◽  
Load Carrying ◽  
Ca Model ◽  
Granular Behavior

Flows of solid granular particles are proposed as an alternate lubrication mechanism to conventional liquid lubrication in sliding contacts, because of their ability to carry loads and to accommodate surface velocities. Alternate lubrication is becoming necessary in extreme temperature environments where liquid lubricants fail and in micro/nanoscale environments were they promote stiction. However understanding granular behavior has been a challenge because of their ability to behave as solids, liquids and gases with varying circumstances. Cellular automata (CA), a deterministic rule based mathematics approach, has been successful in modeling some complex aspects of granular behavior. Our previous work successfully modeled granular shear with CA model. This work introduces a more versatile and novel cellular automata framework which combines the computational efficiency of CA with the power of particle dynamics to capture collision events. In the past, the load carrying capacity of granular flows was demonstrated in the experiments conducted by Yu and Tichy [2] and later, local flow properties were modeled using the granular kinetic lubrication continuum modeling approach. These results were used as a benchmark for determining the effectiveness of the current CA model.

Including Friction and Spin Rules in the Lattice-Based Cellular Automata Approach to Model Granular Flows

2009 ◽  
Author(s):  
Martin C. Marinack ◽  
Venkata K. Jasti ◽  
C. Fred Higgs
Keyword(s):  
Cellular Automata ◽  
Computational Efficiency ◽  
Granular Flow ◽  
Extreme Temperature ◽  
Granular Flows ◽  
Friction Modeling ◽  
Model Collision ◽  
Ca Model ◽  
Granular Behavior ◽  
Multiphase Behavior

Granular flows have been proposed as an alternative lubrication mechanism to conventional liquid lubricants in sliding contacts due to their ability to carry loads and accommodate surface velocities. Their load carrying capacity has been demonstrated in the experiments of Yu and Tichy [1]. Alternate lubrication techniques are becoming necessary due to the failure of conventional liquid lubricants in extreme temperature environments, and their promotion of stiction in micro-/nanoscale environments. Yet, understanding granular behavior has been difficult due to its non-linear and multiphase behavior. Cellular Automata (CA) has been shown to be a viable first order approach to modeling some complex aspects of granular flow. Previous work by the authors successfully modeled granular shear with a CA model [2]. Additional work combined CA computational efficiency with particle dynamics to effectively model collision events. This work builds upon and modifies the prior CA modeling approaches by adding friction modeling and spin of particles. This modification maintains the computational efficiency of CA, while increasing accuracy of the predicted granular flow properties, such as speed, solid fraction, and granular temperature. The current work compares the CA model with friction and spin physics relations to the authors’ prior CA model which neglected friction. Both CA models are also evaluated against experimental data to quantify the benefits of including friction and spin in the CA modeling approach for granular flows.

scholarly journals Experimental and numerical study of granular flow and fence interaction

2004 ◽  
Vol 38 ◽  
pp. 135-138 ◽  
Author(s):  
Thierry Faug ◽  
Mohamed Naaim ◽  
Florence Naaim-Bouvet
Keyword(s):  
Granular Flow ◽  
Numerical Study ◽  
Slope Angle ◽  
Granular Flows ◽  
Snow Avalanches ◽  
Shallow Water Theory ◽  
Gravity Driven ◽  
Deposition Processes ◽  
Set Up ◽  
Good Agreement

AbstractDense snow avalanches are regarded as dry granular flows. This paper presents experimental and numerical modelling of deposition processes occurring when a gravity-driven granular flow meets a fence. A specific experimental device was set up, and a numerical model based on shallow-water theory and including a deposition model was used. Both tools were used to quantify how the retained volume upstream of the fence is influenced by the channel inclination and the obstacle height. We identified two regimes depending on the slope angle. In the slope-angle range where a steady flow is possible, the retained volume has two contributions: deposition along the channel due to the roughness of the bed and deposition due to the fence. The retained volume results only from the fence effects for higher slopes. The effects of slope on the retained volume also showed these two regimes. For low slopes, the retained volume decreases strongly with increasing slope. For higher slopes, the retained volume decreases weakly with increasing slope. Comparison between the experiments and computed data showed good agreement concerning the effect of fence height on the retained volume.

Modeling the spread of an epidemic in presence of vaccination using cellular automata

2022 ◽  
Author(s):  
Agniva Datta ◽  
Muktish Acharyya
Keyword(s):  
Cellular Automata ◽  
Lattice Model ◽  
Present Model ◽  
Mean Field ◽  
Sir Model ◽  
Linear Behavior ◽  
Basic Goal ◽  
Ca Model ◽  
The Mean ◽  
Good Agreement

The results of Kermack–McKendrick SIR model are planned to be reproduced by cellular automata (CA) lattice model. The CA algorithms are proposed to study the model of an epidemic, systematically. The basic goal is to capture the effects of spreading of infection over a scale of length. This CA model can provide the rate of growth of the infection over the space which was lacking in the mean-field like susceptible-infected-removed (SIR) model. The motion of the circular front of an infected cluster shows a linear behavior in time. The correlation of a particular site to be infected with respect to the central site is also studied. The outcomes of the CA model are in good agreement with those obtained from SIR model. The results of vaccination have been also incorporated in the CA algorithm with a satisfactory degree of success. The advantage of the present model is that it can shed a considerable amount of light on the physical properties of the spread of a typical epidemic in a simple, yet robust way.

The Inclusion of Friction in Lattice-Based Cellular Automata Modeling of Granular Flows

2011 ◽  
Vol 133 (3) ◽  
Author(s):  
Martin C. Marinack ◽  
C. Fred Higgs
Keyword(s):  
Cellular Automata ◽  
Granular Flows ◽  
Complex Problem ◽  
Solid Particles ◽  
Particle Interactions ◽  
Dissipative Effects ◽  
Industrial Sectors ◽  
Parametric Studies ◽  
Ca Model ◽  
Solid Liquid

Granular flows continue to be a complex problem in nature and industrial sectors where solid particles exhibit solid, liquid, and gaseous behavior, in a manner which is often unpredictable locally or globally. In tribology, they have also been proposed as lubricants because of their liquid-like behavior in sliding contacts and due to their ability to carry loads and accommodate surface velocities. The present work attempts to model a granular Couette flow using a lattice-based cellular automata computational modeling approach. Cellular automata (CA) is a modeling platform for obtaining fast first-order approximations of the properties of many physical systems. The CA framework has the flexibility to employ rule-based mathematics, first-principle physics, or both to rapidly model physical processes, such as granular flows. The model developed in this work incorporates dissipative effects due to friction between particles and between particles and boundaries, in addition to the derivative effects of friction, namely particle spin. This new model also includes a rigorous and physically relevant treatment of boundary–particle interactions. The current work compares this new friction and spin inclusive CA model and the author’s previous frictionless CA model against experimental results for an annular shear cell. The effects of granular collision properties were also examined through parametric studies on particle–particle coefficient of restitution (COR) and coefficient of friction (COF), which is a unique and added capability of the friction inclusive model.

A GIS-Based Irregular Cellular Automata Model of Land-Use Change

2007 ◽  
Vol 34 (4) ◽  
pp. 708-724 ◽  
Author(s):  
Daniel Stevens ◽  
Suzana Dragićević
Keyword(s):  
Land Use ◽  
Cellular Automata ◽  
Land Use Change ◽  
Spatial Data ◽  
Cellular Automata Model ◽  
Population Growth Rates ◽  
Asynchronous Development ◽  
Canadian City ◽  
Ca Model ◽  
Developing Area

This study proposes an alternative cellular automata (CA) model, which relaxes the traditional CA regular square grid and synchronous growth, and is designed for representations of land-use change in rural-urban fringe settings. The model uses high-resolution spatial data in the form of irregularly sized and shaped land parcels, and incorporates synchronous and asynchronous development in order to model more realistically land-use change at the land parcel scale. The model allows urban planners and other stakeholders to evaluate how different subdivision designs will influence development under varying population growth rates and buyer preferences. A model prototype has been developed in a common desktop GIS and applied to a rapidly developing area of a midsized Canadian city.

scholarly journals Stress level effect on mobility of dry granular flows of angular rock fragments

Landslides ◽  
2021 ◽  
Author(s):  
B. Cagnoli
Keyword(s):  
Stress Level ◽  
Granular Flow ◽  
High Stress ◽  
Granular Flows ◽  
Flow Dynamics ◽  
Small Scale ◽  
Flow Volume ◽  
Rock Fragments ◽  
Rock Avalanches ◽  
Flow Mobility

AbstractGranular flows of angular rock fragments such as rock avalanches and dense pyroclastic flows are simulated numerically by means of the discrete element method. Since large-scale flows generate stresses that are larger than those generated by small-scale flows, the purpose of these simulations is to understand the effect that the stress level has on flow mobility. The results show that granular flows that slide en mass have a flow mobility that is not influenced by the stress level. On the contrary, the stress level governs flow mobility when granular flow dynamics is affected by clast agitation and collisions. This second case occurs on a relatively rougher subsurface where an increase of the stress level causes an increase of flow mobility. The results show also that as the stress level increases, the effect that an increase of flow volume has on flow mobility switches sign from causing a decrease of mobility at low stress level to causing an increase of mobility at high stress level. This latter volume effect corresponds to the famous Heim’s mobility increase with the increase of the volume of large rock avalanches detected so far only in the field and for this reason considered inexplicable without resorting to extraordinary mechanisms. Granular flow dynamics is described in terms of dimensionless scaling parameters in three different granular flow regimes. This paper illustrates for each regime the functional relationship of flow mobility with stress level, flow volume, grain size, channel width, and basal friction.

A Convex Complementarity Approach for Simulating Large Granular Flows

2010 ◽  
Vol 5 (3) ◽  
Author(s):  
Alessandro Tasora ◽  
Mihai Anitescu
Keyword(s):  
Granular Flow ◽  
Complementarity Problems ◽  
Particle Interaction ◽  
Granular Flows ◽  
Rigid Bodies ◽  
Integration Time ◽  
Frictional Contacts ◽  
Physical Experiments ◽  
Dense Granular Flow ◽  
Number Of Particles

Aiming at the simulation of dense granular flows, we propose and test a numerical method based on successive convex complementarity problems. This approach originates from a multibody description of the granular flow: all the particles are simulated as rigid bodies with arbitrary shapes and frictional contacts. Unlike the discrete element method (DEM), the proposed approach does not require small integration time steps typical of stiff particle interaction; this fact, together with the development of optimized algorithms that can run also on parallel computing architectures, allows an efficient application of the proposed methodology to granular flows with a large number of particles. We present an application to the analysis of the refueling flow in pebble-bed nuclear reactors. Extensive validation of our method against both DEM and physical experiments results indicates that essential collective characteristics of dense granular flow are accurately predicted.

scholarly journals A Cellular Automata Model for Integrated Simulation of Land Use and Transport Interactions

2021 ◽  
Vol 10 (3) ◽  
pp. 149
Author(s):  
Nuno Pinto ◽  
António P. Antunes ◽  
Josep Roca
Keyword(s):  
Land Use ◽  
Cellular Automata ◽  
Land Use Change ◽  
Urban Studies ◽  
Particle Swarm Algorithm ◽  
Cellular Automata Model ◽  
Integrated Simulation ◽  
The Road ◽  
Ca Model ◽  
The City

Cellular automata (CA) models have been used in urban studies for dealing with land use change. Transport and accessibility are arguably the main drivers of urban change and have a direct influence on land use. Land use and transport interaction models deal with the complexity of this relationship using many different approaches. CA models incorporate these drivers, but usually consider transport (and accessibility) variables as exogenous. Our paper presents a CA model where transport variables are endogenous to the model and are calibrated along with the land use variables to capture the interdependent complexity of these phenomena. The model uses irregular cells and a variable neighborhood to simulate land use change, taking into account the effect of the road network. Calibration is performed through a particle swarm algorithm. We present an application of the model to a comparison of scenarios for the construction of a ring road in the city of Coimbra, Portugal. The results show the ability of the CA model to capture the influence of change of the transport network (and thus in accessibility) in the land use dynamics.

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