Image based modelling of lateral magma flow: the Basement Sill, Antarctica

The McMurdo Dry Valleys magmatic system, Antarctica, provides a world-class example of pervasive lateral magma flow on a continental scale. The lowermost intrusion (Basement Sill) offers detailed sections through the now frozen particle microstructure of congested magma slurry. We simulated the flow regime in 2 and 3D using numerical models built on a finite element mesh derived from field data. The model captures the flow behaviour of the Basement Sill magma over a viscosity range of 1-104 Pa s where the higher end (≥102 Pa s) corresponds to a magmatic slurry with crystal fractions varying between c. 30 and 70%. A novel feature of the model is the discovery of transient, low viscosity (≤ 50 Pa s) high Reynolds number eddies formed along undulating contacts at the floor and roof of the intrusion. Numerical tracing of particle orbits implies crystals trapped in eddies segregate according to their mass density. Recovered shear strain rates (10 3 to 10-5 s-1) at viscosities equating to high particle concentrations (> c. 40%) in the Sill interior point to shear-thinning as an explanation for some types of magmatic layering there. Model transport rates for the Sill magmas imply a maximum emplacement time of c. 105 years, consistent with geochemical evidence for long range lateral flow. It is a theoretically possibility that fast-flowing magma on a continental scale will be susceptible to planetary-scale rotational forces

A study into the influence of the car geometry on the aerodynamic transient effects arising in a high rise lift installation

One of the main goals in designing a high-speed lift system is developing a more aerodynamically efficient car geometry that guarantees a good ride comfort and reduces the energy consumption. In this study, a three-dimensional computational fluid dynamics (CFD) model has been developed to analyse an unsteady turbulent air flow around two cars moving in a lift shaft. The paper is focused on transient aerodynamic effects arising when two cars pass each other in the same shaft at the same speed. The scenarios considered in the paper involve cars having three different geometries. Aerodynamic forces such as the drag force that occur due to the vertical opposite motions of the cars have been investigated. Attention is paid to the airflow velocity and pressure distribution around the car structures. The flow pattern in the boundary layer around each car has been calculated explicitly to examine the flow separation in the wake region. The results presented in the paper would be useful to guide the lift designers to understand and mitigate the aerodynamic effects arising in the lift shaft

Modelling, simulation and experimental validation of nonlinear dynamic interactions in an aramid rope system

Vibration phenomena taking place in lifting and hoist installations may influence the dynamic performance of their components. For example, in an elevator system they may affect ride quality of a lift car. Lateral and longitudinal vibrations of suspension ropes and compensating cables may result in an adverse dynamic behaviour of the entire installation. Thus, there is a need to develop reliable mathematical and computer simulation models to predict the dynamic behaviour of suspension rope and compensating cable systems. The aim of this paper is to develop a model of an aramid suspension rope system in order to predict nonlinear modal interactions taking place in the installation. A laboratory model comprising an aramid suspension rope, a sheave/pulley assembly and a rigid suspended mass has been studied. Experimental tests have been conducted to identify modal nonlinear couplings in the system. The dynamic behaviour of the model has been described by a set of nonlinear partial differential equations. The equations have been solved numerically. The numerical results have been validated by experimental tests. It has been shown that the nonlinear couplings may lead to adverse modal interactions in the system

Data from: Image based modelling of lateral magma flow: the Basement Sill, Antarctica

The McMurdo Dry Valleys magmatic system, Antarctica, provides a world-class example of pervasive lateral magma flow on a continental scale. The lowermost intrusion (Basement Sill) offers detailed sections through the now frozen particle microstructure of a congested magma slurry. We simulated the flow regime in two and three dimensions using numerical models built on a finite-element mesh derived from field data. The model captures the flow behaviour of the Basement Sill magma over a viscosity range of 1–104 Pa s where the higher end (greater than or equal to 102 Pa s) corresponds to a magmatic slurry with crystal fractions varying between 30 and 70%. A novel feature of the model is the discovery of transient, low viscosity (less than or equal to 50 Pa s) high Reynolds number eddies formed along undulating contacts at the floor and roof of the intrusion. Numerical tracing of particle orbits implies crystals trapped in eddies segregate according to their mass density. Recovered shear strain rates (10−3–10−5 s−1) at viscosities equating to high particle concentrations (around more than 40%) in the Sill interior point to shear-thinning as an explanation for some types of magmatic layering there. Model transport rates for the Sill magmas imply a maximum emplacement time of ca 105 years, consistent with geochemical evidence for long-range lateral flow. It is a theoretically possibility that fast-flowing magma on a continental scale will be susceptible to planetary-scale rotational forces

Modelling, simulation and experimental validation of nonlinear dynamic interactions in an aramid rope system

Vibration phenomena taking place in lifting and hoist installations may influence the dynamic performance of their components. For example, in an elevator system they may affect ride quality of a lift car. Lateral and longitudinal vibrations of suspension ropes and compensating cables may result in an adverse dynamic behaviour of the entire installation. Thus, there is a need to develop reliable mathematical and computer simulation models to predict the dynamic behaviour of suspension rope and compensating cable systems. The aim of this paper is to develop a model of an aramid suspension rope system in order to predict nonlinear modal interactions taking place in the installation. A laboratory model comprising an aramid suspension rope, a sheave/ pulley assembly and a rigid suspended mass has been studied. Experimental tests have been conducted to identify modal nonlinear couplings in the system. The dynamic behaviour of the model has been described by a set of nonlinear partial differential equations. The equations have been solved numerically. The numerical results have been validated by experimental tests. It has been shown that the nonlinear couplings may lead to adverse modal interactions in the system

Computer simulation model of a lift car assembly with an active tuned mass damper

In engineering systems a Passive Tuned Mass Damper (a secondary mass – spring - damper combination) is often used to reduce vibrations of a primary structure (main mass). In an Active Tuned Mass Damper (ATMD) arrangement vibrations of the main mass are attenuated when the secondary mass (referred to as an active mass) is actively controlled. The ATMD system is equipped with a controller, sensors and an actuator. The attenuation is achieved by the application of control force determined by a suitable feedback control algorithm. In this paper the ATMD method is considered to attenuate resonance vertical vibrations of a lift car assembly – suspension rope system during the lift travel, when the frequency of harmonic excitation acting upon the car assembly becomes near its natural frequency. A mathematical model with the optimal feedback gain calculated using Linear–Quadratic Regulator control law is developed. Then, a case study is presented in which computer simulation is carried out. The simulation results are discussed and the effectiveness of an active tuned mass damper system is demonstrated for a given set of lift system parameters

Mathematical modelling and computer simulation of nonlinear behaviour of a hoisting cable system

A hoisting installation represents a multi-body system deployed to provide vertical transportation. Vibration phenomena taking place in hoist installations may influence their dynamic performance. In particular lateral and longitudinal vibrations of suspension cables may result in an adverse dynamic behaviour of the entire installation. The aim of this paper is to develop a multibody dynamics model of a hoisting cable system in order to predict its nonlinear behaviour. The model comprises an aramid suspension cable, a sheave/ pulley assembly and a rigid suspended mass. The dynamic response of the model is described by a set of nonlinear partial differential equations which is treated using the Galerkin method and numerical integration. Subsequently, an ADAMS simulation model has been used to validate the theoretical model. A laboratory system has also been developed and experimental tests have been conducted to identify the dynamic characteristics and to quantify the response of the system. It is shown that the numerical solutions are in good agreement with the ADAMS simulation results and with the results of experimental tests. Subsequently a suitable vibration control can be sought to mitigate the effects of nonlinear interactions taking place in the system