Development of a New Contact Angle Control Algorithm for Level-Set Method

2018 ◽  
Vol 141 (6) ◽  
Author(s):  
Mengnan Li ◽  
Kaiyue Zeng ◽  
Louis Wonnell ◽  
Igor A. Bolotnov
Keyword(s):  
Contact Angle ◽  
Control Algorithm ◽  
Force Model ◽  
Flat Plates ◽  
Flow Solver ◽  
Evaporation And Condensation ◽  
Condensation Algorithm ◽  
Current Contact ◽  
Mesh Resolution ◽  
Structured Meshes

A contact angle control algorithm is developed and implemented in the multiphase interface tracking flow solver—phasta. The subgrid force model is introduced to control the evolving contact angle. The contact angle force is applied when the current contact angle deviates from the desired value (or range of values) and decreases to zero when it reaches the desired value. The single bubble departure simulation and the capillary flat plates simulation are performed for verification purpose. The numerical results are compared with the analytical solution with good agreement. The mesh resolution sensitivity analysis and parametric study are conducted for both simulations. Coupled with the other existing capabilities in phasta like evaporation and condensation algorithm, the contact angle control algorithm will allow us to investigate the boiling phenomenon in various conditions with lower cost (by utilizing localized mesh refinement for bubble growth region) compared to uniformly refined structured meshes and in engineering geometries.

Online Parameter Estimation of the Lankarani–Nikravesh Contact Force Model Using Two Different Methods

2016 ◽  
Vol 13 (04) ◽  
pp. 1641017 ◽  
Author(s):  
Jia Ma ◽  
Linfang Qian ◽  
Guangsong Chen
Keyword(s):  
Parameter Estimation ◽  
Contact Force ◽  
Unscented Kalman Filter ◽  
Initial Conditions ◽  
Linear Method ◽  
Estimation Method ◽  
Recursive Least Squares ◽  
Force Model ◽  
Contact Force Model ◽  
Current Contact

Current contact force models are expected to be used under different environments, where the dynamical parameter estimation becomes an important issue in accurately analyzing the overall behavior of mechanical system especially for complex contact situations. In recent years, a significant amount of research has been carried out in relation to the nonlinear inverse problems, which can be generally divided into two categories: one is the linear method and the other can be called the nonlinear one. In this paper, both methods are described and compared. The linear method is based on the Taylor series and Exponentially Weighted Recursive Least Squares (EWRLS) estimation method. Whereas, the core of the nonlinear one is the Unscented Kalman Filter (UKF). The Lankarani–Nikravesh (L–N) contact force model is employed to quantify the contact effect in this paper, since it is proven to be more consistent with the physics of contact. Some simulation examples are employed to evaluate the convergence sensitivity of these two methods to parameter initial conditions. And the comparisons under the same simulation condition between both methods indicate that the nonlinear one is more robust and can converge faster than the linear one.

scholarly journals VOF simulations of the contact angle dynamics during the drop spreading: Standard models and a new wetting force model

2014 ◽  
Vol 212 ◽  
pp. 1-20 ◽  
Author(s):  
Ilias Malgarinos ◽  
Nikolaos Nikolopoulos ◽  
Marco Marengo ◽  
Carlo Antonini ◽  
Manolis Gavaises
Keyword(s):  
Contact Angle ◽  
Force Model ◽  
Drop Spreading ◽  
Standard Models ◽  
Wetting Force

Surface Tension Capability Within an Adaptively Refined Compressible Flow Code

2017 ◽  
Author(s):  
Z. Jibben ◽  
J. Velechovsky ◽  
T. Masser ◽  
M. Francois
Keyword(s):  
Surface Tension ◽  
Compressible Flow ◽  
Piecewise Linear ◽  
Surface Force ◽  
Force Model ◽  
Material Interface ◽  
Flow Solver ◽  
Interface Reconstruction ◽  
Volume Method ◽  
Inviscid Compressible Flow

We present a method to simulate surface tension between immiscible materials within an inviscid compressible flow solver. The material interface is represented using the volume of fluid technique with piecewise-linear interface reconstruction. We employ the continuum surface force model for surface tension, implemented in the context of the MUSCL-Hancock finite volume method for the Euler equations on an adaptively refined Eulerian mesh. We show results for droplet verification test cases.

scholarly journals A conservative saint-venant type model to describe the dynamics of thin partially wetting films with regularized forces at the contact line

2020 ◽  
Vol 69 ◽  
pp. 79-103
Author(s):  
Pierre Trontin ◽  
Julien Lallement ◽  
Philippe Villedieu
Keyword(s):  
Contact Angle ◽  
Contact Line ◽  
Driving Forces ◽  
Mesh Size ◽  
Capillary Forces ◽  
Liquid Films ◽  
Industrial Applications ◽  
Type Model ◽  
Finite Volume Scheme ◽  
Mesh Resolution

This paper deals with the numerical simulation of thin liquid films flowing on partially wetting solid substrates. A 2D Saint-Venant like model is proposed. Its originality lies in the conservative formulation of the capillary forces and in the model used for the disjoining pressure that accounts for the contact line capillary forces. A finite volume scheme is proposed for the resolution of the system and various numerical examples are presented and discussed. In particular, when the mesh resolution is fine enough, the model is proved to be able to predict correctly the spreading of a film with the exact contact angle in the vicinity of the contact line. When the mesh size is larger than the film thickness (which could be the case for many industrial applications), it is of course no longer possible to recover the contact angle. However, the model is proved to correctly predict the spreading of the film. This important feature is related to the thermodynamic consistency of the model in the sense that the latter ensures by construction the decrease of the film total free energy in the absence of external driving forces.

Mitigation of Biodynamic Response to Shock Loads Using Semi-Active Vertically Stroking Crew Seats

2010 ◽  
Author(s):  
Harinder J. Singh ◽  
Norman M. Wereley
Keyword(s):  
Human Body ◽  
Control Algorithm ◽  
Equations Of Motion ◽  
Comprehensive Analysis ◽  
Lumped Parameter Model ◽  
Force Model ◽  
Body Parts ◽  
Governing Equations ◽  
Lumped Parameter ◽  
Yield Force

This study addresses mitigation of biodynamic response due to an initial velocity impact of a vertically stroking crew seat using an adaptive magnetorheological energy absorber. Under consideration is a multiple degree-of-freedom detailed lumped parameter model of a human body falling with prescribed initial crash velocity (sink rate). The lumped parameter model of the human body consisted of four main parts: pelvis, upper torso, viscera and head. The governing equations of motion of a vertically stroking crew seat incorporating a human body were derived using parameters such as available damper stroke as well as MR yield force. The control algorithm for smooth landing of a rigid occupant was examined for compliant occupant and was modified accordingly. Four MR yield force models were analyzed to shape decelerations experienced by human body and an appropriate model was selected for comprehensive analysis. The simulated responses were analyzed with selected MR yield force model for a crew seat with an occupant corresponding to 90th percentile male at sink rates varying from 8 to 12 m/s. In addition, the mitigation of injuries to the human body parts due to load transmissions corresponding to crash velocities was also evaluated for the selected MR yield force model along with terminal conditions necessary for smooth landing.

scholarly journals An Improved Procedure for Strongly Coupled Prediction of Sailing Yacht Performance

2021 ◽  
Vol 6 (01) ◽  
pp. 133-150
Author(s):  
A. Persson ◽  
L. Larsson ◽  
C. Finnsgård
Keyword(s):  
Free Surface ◽  
Wind Speed ◽  
Control Algorithm ◽  
Body Motion ◽  
Force Model ◽  
Strongly Coupled ◽  
Performance Predictions ◽  
Correct Alignment ◽  
Sailing Yacht ◽  
Background Grid

Abstract In this paper, an improved procedure for strongly coupled prediction of sailing yacht performance is developed. The procedure uses 3D RANS CFD to compute the hydrodynamic forces. When coupled to a rigid body motion solver and a sail force model, along with a rudder control algorithm, this allows sailing yacht performance to be predicted within CFD software. The procedure provides improved convergence when compared to a previously published method. The grid motion scheme, partially using overset grid techniques, means that correct alignment between the free surface and the background grid is ensured even at large heel angles. The capabilities are demonstrated with performance predictions for the SYRF 14 m yacht, at one true wind speed, over a range of true wind angles, with up- and downwind sailsets. The results are compared to predictions from the ORC-VPP for a yacht with similar main particulars.

Parametric Effects of Heater Size, Contact Angle, and Surrounding Vessel Size On Pool Boiling Critical Heat Flux From Horizontal Surfaces

2021 ◽  
Author(s):  
Zhenyu She ◽  
Vijay K. Dhir
Keyword(s):  
Heat Flux ◽  
Contact Angle ◽  
Critical Heat Flux ◽  
Nucleate Boiling ◽  
Flat Plates ◽  
Vessel Size ◽  
Saturated Water ◽  
Nucleate Boiling Heat Transfer ◽  
Parametric Effects ◽  
Glass Tubes

Abstract Saturated water at one atmosphere pressure was boiled on horizontal copper discs of diameters 1.0,1.5 and 2.0 cm. respectively. The contact angle was varied from 10 to 80 degrees by controlling thermal oxidation of the discs, while the surrounding vessel size was changed by placing glass tubes of different inner diameters around the discs. Nucleate boiling heat transfer data were obtained up to critical heat flux (CHF), where vapor removal patterns were photographed. Dominant wavelengths at vapor jet interface and vapor jet diameters were measured from the photographs of the well wetted discs. For a well wetted surface, the magnitude of CHF increased when the heater size was reduced from 2.0 to 1.0 cm. Improving the wettability enhanced the CHF substantially, whereas the increased size of the liquid holding vessel had a smaller effect. The highest measured CHF is 233 W/cm2 or 2.11 times Zuber's CHF prediction for infinite horizontal flat plates. It was obtained on a 1.0 cm. disc of contact angle about 10 degrees surrounded by a large vessel. The CHF for this surface was increased from 201 to 233 W/cm2 when the ratio of heater size to surrounding vessel size was reduced from 1 to about 0.

The Importance of Spinning Friction in Thrust-Carrying Ball Bearings

1960 ◽  
Vol 82 (2) ◽  
pp. 295-300 ◽  
Author(s):  
G. S. Reichenbach
Keyword(s):  
Contact Angle ◽  
Experimental Work ◽  
Major Part ◽  
Ball Bearing ◽  
Thrust Bearing ◽  
Contact Angles ◽  
Ball Bearings ◽  
Flat Plates ◽  
Theoretical Predictions ◽  
Rolling Balls

Experimental work was done rolling balls on flat plates and in V-grooves at loads and contact angles corresponding to usual thrust-bearing practice. It is shown that the spinning action of the ball with respect to the race should account for the major part of the over-all friction of a thrust-carrying ball bearing. Variables studied included contact angle, conformity, load, lubricant, and temperature. The results have been correlated and shown to follow theoretical predictions.

A Feasibility Study of Life-Extending Controls for Aircraft Turbine Engines Using a Generic Air Force Model

2006 ◽  
Author(s):  
Al Behbahani ◽  
Eric A. Jordan ◽  
Richard Millar
Keyword(s):  
Air Force ◽  
Control Algorithm ◽  
Fuel Efficiency ◽  
Operating Cost ◽  
Performance Criterion ◽  
Turbine Engines ◽  
Force Model ◽  
Stability Margins ◽  
Turbine Engine ◽  
Damage Models

Turbine engine controllers are typically designed and operated to meet required or desired performance criterion within stability margins, while maximizing fuel efficiency. The U.S. Air Force turbine engine research program is seeking to incorporate sustainable cost reduction into this approach, by considering a life-cycle design objective if the life of the engine is considered as an objective during the design of the engine controller. Specifically during aircraft takeoff, the turbine engines are subject to high temperature variations that aggravate the stress of the material used in their construction and thus a negative effect in their life spans. Therefore, the control strategy needs to be re-evaluated to include operating cost, and extending the life of the engine is one way to reduce that. Life-Extending Control (LEC) is an area that deals with control action, engine component life usage, and designing an intelligent control algorithm embedded in the FADEC. This paper evaluates the LEC, based on critical components research, to demonstrate how an intelligent engine control algorithm can drastically reduce the engine life usage, with minimum sacrifice in performance. Finally, a generic turbine engine is extensively simulated using a sophisticated non-linear model of the turbine engine. The paper concludes that LEC is worth consideration and further research should include development of the damage models for turbine engines, and experimental research that could correlate the damage models to actual damage for turbine engines. This could lead to implementation of online damage models in real-time that will allow for more robust damage prevention.

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