Assessment of casting filling by modeling surface entrainment events using CFD

The reliability of cast components is dependent on the quality of the casting process. During this highly transient filling phase the prevention of free surface turbulence and consequential oxide entrainment is critical to ensure the mechanical integrity of the component. Past research has highlighted a number of events that lead to entrainment of surface oxides. Using FLOW-3D, flow structures that result in surface entrainment events have been simulated and an algorithm developed that allows entrainment and defect motion to be tracked. This enables prediction of the quantity and motion of oxide film generated from each event. The algorithm was tested experimentally and compared to experimental data from previously published work. A quantitative criterion is proposed to assess the damage of each type of event. Complete running systems have also been studied to understand how they could be assessed for quality of filling based on the flows within them

Electroconvective instability in a fluid layer

Electroconvective instabilities in fluid laye

The modelling of oxide film entrainment in casting systems using computational modelling

As Campbell stated in 2006, “the use of entrainment models to optimise filling systems designs for castings has huge commercial potential that has so far being neglected by modellers”. In this paper a methodology using computational modelling to define entraining events and track the entrained oxide films is presented. Research has shown that these oxide films present within the casting volume are highly detrimental to casting integrity, thus their entrainment during mould filling is especially undesirable. The method developed for the modelling of oxide entrainment has been validated against previously published data by Green and Campbell (1994) [31]. The validation shows good quantitative correlation with experimental data. However there is scope for further development which has the potential to both improve the accuracy and further validate the technique

Quality assesment of casting filling method

The reliability of cast components is dependent on the quality of the casting process. This can be characterised by the robustness (repeatability) and specific fluid flow characteristics within the running system. During this transient filling phase the prevention of free surface turbulence and thus oxide entrainment is critical to the mechanical integrity of the component [1,2,3]. Past research has highlighted that return waves are major causes of free surface entrainment [4]. To reduce the entrainment occurring during the transitional filling of the runner a steady quiescent flow must be developed. Using FLOW-3D(1), the Froude number was extracted to allow the quantitative assessment of air entrainment for four different designs of sump at the end of the runner. The results show that, for the designs used, the addition of a correctly designed sump can be advantageous. However, an incorrect design may reduce the Froude number but can greatly increase the persistence of the return wave and entrainment and is therefore extremely detrimental to the cast component. Additionally, the in-gate design is of utmost importance in controlling the back pressure and thus the persistence of the back wave between the in-gate and the downsprue exit. This has a direct effect of the level of oxide entrainment

Anti-CTLA-4 (CD 152) monoclonal antibody-induced autoimmune interstitial nephritis

Targeted immune-modulating agents are entering clinical practice in many specialties, providing novel therapeutic possibilities but introducing new potential toxicities. We present the first reported case, to our knowledge, of immune-mediated nephritis following the administration of Tremelimumab (CP-675, 206), an anti-cytotoxic T-lymphocyte-associated antigen 4 (CTLA-4) monoclonal antibody. High-dose steroid therapy led to a rapid improvement in renal function, avoiding the need for renal replacement therapy.Peer reviewe

A Purely Functional Computer Algebra System Embedded in Haskell

We demonstrate how methods in Functional Programming can be used to implement a computer algebra system. As a proof-of-concept, we present the computational-algebra package. It is a computer algebra system implemented as an embedded domain-specific language in Haskell, a purely functional programming language. Utilising methods in functional programming and prominent features of Haskell, this library achieves safety, composability, and correctness at the same time. To demonstrate the advantages of our approach, we have implemented advanced Gr\"{o}bner basis algorithms, such as Faug\`{e}re's $F_4$ and $F_5$, in a composable way.Comment: 16 pages, Accepted to CASC 201

Investigating surface entrainment events using CFD for the assessment of casting filling methods

The reliability of cast components is dependent on thequality of the casting process. This can be characterised by the robustness (repeatability) and specific fluid flow characteristics within the running system and mould cavity. During this highly transient filling phase the prevention of free surface turbulence and consequential oxide entrainment is critical to assure the mechanical integrity of the component. Past research has highlighted a number of events that lead to entrainment of surface oxides, including plungingjets, waterfalls and returning backwaves. Using FLOW-3D, flow structures that result in surface entrainment events have been simulated and an algorithm developed that allows entrainment and defect motion to be tracked. This enables prediction of the quantity and motion of oxide film generated from each event. The algorithm was tested experimentally using real-time X-ray radiography to directly image transient liquid metal flows. A quantitative criterion is proposed in order to be able to assess the damage of each type of event. Complete running systems have also been studied in order to understand how they could be assessed for quality of filling based on the geometric features of the flows within them

A determining form for the two-dimensional Navier-Stokes equations: The Fourier modes case

The determining modes for the two-dimensional incompressible Navier-Stokes equations (NSE) are shown to satisfy an ordinary differential equation (ODE) of the form $dv/dt = F(v)$, in the Banach space, $X$, of all bounded continuous functions of the variable $s\in\mathbb{R}$ with values in certain finite-dimensional linear space. This new evolution ODE, named determining form, induces an infinite-dimensional dynamical system in the space $X$ which is noteworthy for two reasons. One is that $F$ is globally Lipschitz from $X$ into itself. The other is that the long-term dynamics of the determining form contains that of the NSE; the traveling wave solutions of the determining form, i.e., those of the form $v(t, s) = v_{0}(t + s)$, correspond exactly to initial data $v_{0}$ that are projections of solutions of the global attractor of the NSE onto the determining modes. The determining form is also shown to be dissipative; an estimate for the radius of an absorbing ball is derived in terms of the number of determining modes and the Grashof number (a dimensionless physical parameter)

Highly ordered good crystalline ZnO-doped WO3 thin films suitable for optoelectronic applications.

Highly ordered ZnO-doped WO3 thin films with good crystalline quality are prepared using radio frequency magnetron sputtering technique, and its morphological and structural properties are studied using various characterization tools such as field emission scanning electron microscopy, energy-dispersive x-ray spectroscopy, x-ray diffraction technique, micro-Raman spectroscopy, and x-ray photoelectron spectroscopy. Morphological analysis shows a smooth surface for pure film, whereas the ZnO-doped films presents a dense distribution of grains of larger sizes with well-defined grain boundary. X-ray diffraction studies reveal the enhancement of crystalline quality of the films with increase in ZnO doping concentration up to 5 wt.%, beyond which the crystalline quality gets deteriorated. A phase modification from a single monoclinic WO3 phase to mixed monoclinic WO3 and W18O49 phases is observed for films with higher ZnO doping concentrations