Simulent Inc.

Toronto, Canada

Simulent Inc.

Toronto, Canada

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Farrokhpanah A.,University of Toronto | Samareh B.,Simulent Inc. | Mostaghimi J.,University of Toronto
Journal of Fluids Engineering, Transactions of the ASME | Year: 2015

Equilibrium contact angle of liquid drops over horizontal surfaces has been modeled using smoothed particle hydrodynamics (SPH). The model is capable of accurate implementation of contact angles to stationary and moving contact lines. In this scheme, the desired value for stationary or dynamic contact angle is used to correct the profile near the triple point. This is achieved by correcting the surface normals near the contact line and also interpolating the drop profile into the boundaries. Simulations show that a close match to the chosen contact angle values can be achieved for both stationary and moving contact lines. This technique has proven to reduce the amount of nonphysical shear stresses near the triple point and to enhance the convergence characteristics of the solver. Copyright © 2015 by ASME.


Parizi H.B.,Simulent Inc. | Mostaghimi J.,University of Toronto | Pershin L.,University of Toronto | Jazi H.S.,University of Toronto
Journal of Thermal Spray Technology | Year: 2010

Microstructure of coatings produced by thermal spray coating process depends on many parameters, including particle impact conditions, powder materials, and substrate conditions. Because of the large number of parameters affecting microstructure, developing a computational tool that can predict the microstructure of thermal spray coatings as a function of these parameters can be of great interest as it will save time and resources when developing new coatings. In this article, we examine the validity and the accuracy of such a computational tool. We present the result of a three-dimensional model of coating formation. The model is based on the Monte Carlo method with particle impact conditions, materials properties of powder, and substrate as input. The output of the model includes coating porosity, surface roughness, and coating thickness. In order to validate the model, coatings under specific conditions were deposited and the predicted results were compared to the actual deposits. The impact conditions for these cases were measured by DPV-2000 and the raw data were used as input to the computer program. The comparison between the actual deposits and the simulated ones shows good agreement. The results demonstrate the viability and usefulness of this modeling tool in developing new coatings and understanding their microstructure. © ASM International.


Kowsari K.,King's College | Nouraei H.,King's College | Samareh B.,Simulent Inc. | Papini M.,King's College | And 3 more authors.
Ceramics International | Year: 2016

The extreme hardness of sintered ceramics makes it difficult to machine them economically. Abrasive slurry-jet micro-machining (ASJM), in which a target is eroded by the impingement of a micro-jet of water containing fine abrasive particles, is a low-cost alternative for micro-machining of sintered ceramic materials without tool wear and thermal damage, and without the use of patterned masks. Existing profile prediction models could not account for changes in the flow field observed in the ASJM of sintered ceramics as channel depth increased. These changes in the flow of abrasive particles fundamentally altered the channel profiles so that the specific erosion rate (mass of material removed per mass of erodent) of the channel centerline decreased with increasing depth and, when machined at 90° incidence, the profiles changed shape. Computational fluid dynamic (CFD) modeling was used to derive a generalized relation between channel geometry and erosive flow (the nonlinearity function), which was used in an existing numerical-empirical model to predict the depths, widths, and shapes of ASJM micro-channels in sintered ceramics; i.e. aluminum nitride (AlN), alumina (Al2O3), and zirconium tin titanate (Zn-Sn-TiO2). The specific erosion rate-particle impact angle and specific erosion rate-particle impact velocity relations, measured for 1 wt%, 10 μm-diameter alumina slurry jet, were used in a CFD model of a first-pass channel to obtain the erosive pattern (erosive efficacy distribution) of the slurry jet within a shallow ceramic channel. This shallow, first-pass erosion pattern was then generalized and used with the nonlinearity function to predict the shapes of deeper channels. The predicted depths in each of the three ceramics at any point on the cross-section were within 6% of those of measured channels up to a depth/width aspect ratio of about 0.5 for nozzle angles of both 90° and 45° in both the forward or backward channel-machining configurations. © 2016 Elsevier Ltd and Techna Group S.r.l.


Kowsari K.,King's College | Nouraei H.,King's College | Samareh B.,Simulent Inc. | Papini M.,King's College | Spelt J.K.,King's College
Ceramics International | Year: 2016

The extreme hardness of sintered ceramics makes it difficult to machine them economically. Abrasive slurry-jet micro-machining (ASJM), in which a target is eroded by the impingement of a micro-jet of water containing fine abrasive particles, is a low-cost alternative for micro-machining of sintered ceramic materials without tool wear and thermal damage, and without the use of patterned masks. Existing profile prediction models could not account for changes in the flow field observed in the ASJM of sintered ceramics as channel depth increased. These changes in the flow of abrasive particles fundamentally altered the channel profiles so that the specific erosion rate (mass of material removed per mass of erodent) of the channel centerline decreased with increasing depth and, when machined at 90° incidence, the profiles changed shape. Computational fluid dynamic (CFD) modeling was used to derive a generalized relation between channel geometry and erosive flow (the nonlinearity function), which was used in an existing numerical-empirical model to predict the depths, widths, and shapes of ASJM micro-channels in sintered ceramics; i.e. aluminum nitride (AlN), alumina (Al2O3), and zirconium tin titanate (Zn-Sn-TiO2). The specific erosion rate-particle impact angle and specific erosion rate-particle impact velocity relations, measured for 1wt%, 10μm-diameter alumina slurry jet, were used in a CFD model of a first-pass channel to obtain the erosive pattern (erosive efficacy distribution) of the slurry jet within a shallow ceramic channel. This shallow, first-pass erosion pattern was then generalized and used with the nonlinearity function to predict the shapes of deeper channels. The predicted depths in each of the three ceramics at any point on the cross-section were within 6% of those of measured channels up to a depth/width aspect ratio of about 0.5 for nozzle angles of both 90° and 45° in both the forward or backward channel-machining configurations. © 2016 Elsevier Ltd and Techna Group S.r.l.


Lin E.,University of Toronto | Parizi H.B.,Simulent Inc. | Pourmousa A.,Simulent Inc. | Chandra S.,University of Toronto | Mostaghimi J.,University of Toronto
Journal of Coatings Technology Research | Year: 2011

Applying a thin, protective coating of a nontoxic, chemically resistant epoxy to the interior of existing pipes is an alternative method to pipe replacement. In order to find the controlling parameters in this method, in this study, viscous epoxy was propelled by compressed air through clear polyvinyl chloride (PVC) pipes. Epoxy flow was annular, and it hardened to form a thin, uniform coating on the inner pipe surface. A video camera was employed to record fluid motion, and the thickness of the coating was measured using an image analysis program named ImagJ. Tests were done with varying air temperature, airflow rate, piping configuration, and epoxy temperature. A one-dimensional numerical algorithm was developed to model fluid flow, heat transfer, and epoxy curing. Heating the epoxy makes it move faster because liquid viscosity decreases with increasing temperature. The coating was significantly thicker at the bottom of a horizontal pipe than at the top due to sagging of the epoxy coating after it had been applied, resulting in flow from the top to the bottom of the pipe. Sagging could be reduced by maintaining airflow until curing was almost complete and the epoxy had hardened enough to prevent it from moving easily. The combination of the experimental results and numerical modeling showed that the most important parameters controlling the speed of the epoxy and coating thickness were the air flow rate and temperature, since they determine the shear forces on the epoxy layer and the rate at which the epoxy cures. Raising air temperature increases the reaction rate and therefore decreases the time required for the epoxy to cure inside the pipe. The results of the simulation showed a very good agreement with the experimental results in pipes with 1-in diameter or less. © 2011 ACA and OCCA.

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