Extraction, Purification, Bioactivities and Application of Matrix Proteins From Pearl Powder and Nacre Powder: A Review

Natural pearls are formed when sand or parasites (irritants) accidentally enter into the oyster body and form pearls under the cover of the nacre layer. Pearl powder is a powdery substance by grinding pearls into small grains, however, the nacre powder is the inner layer of outer corner layer and middle prism layer. Pearl medicine in China has a history of more than 2,000 years, pearl has the effects of calming the mind, clearing the eyes, detoxifying the muscle and so on. In this paper, the researches on the extraction of pearl powder and nacre powder, the isolation and purification of matrix protein and the various biological activities (osteogenic activity, antioxidant, anti-inflammatory, anti-apoptotic, promoting the migration of fibroblasts, and so on) are reviewed in detail. To provide readers with a faster understanding, the method of extraction and purification and the application of nacre powder and pearl powder are clearly presented in the form of figures and tables. In line with the concept of waste or by-product, there are more reports of nacre extract than pearl extract, due to the expensive and limited in origin of pearls. Mainly on the direct use of nacre powder and pearl powder or on the use of extracts (mainly water soluble proteins) through experiments in vivo or in vitro, and shows whether it is effective through the results of various indexes. There is no further study on substances other than extracts, and the structural analysis of extracts needs further exploration.

Minimising Numerical Ventilation in CFD Simulations of High-speed Planing Hulls

Numerical Ventilation (NV) is a well-known problem that occurs when the Volume of Fluid method is used to model vessels with a bow that creates an acute entrance angle with the free surface, as is typical for both planing hulls and yachts. Numerical Ventilation may be considered one of the main sources of error in numerical simulations of planing hulls and as such warrants an in-depth analysis. This paper sets out to bring together the available work, as well as performing its own investigation into the problem to develop a better understanding of Numerical Ventilation and present alternate solutions. Additionally, the success and impact of different approaches is presented in an attempt to help other researchers avoid and correct for Numerical Ventilation. Interface smearing caused by the simulation being unable to track the free surface is identified as the main source of Numerical Ventilation. This originates from the interface between the volume mesh and the prism layer mesh. This study investigates this interface, presenting a novel solution to prism layer meshing that was found to minimize Numerical Ventilation. Through the implementation of a modified High Resolution Interface Capture (HRIC) scheme and the correct mesh refinements, it is possible to minimize the impact of Numerical Ventilation to a level that will not affect the results of a simulation and is acceptable for engineering applications.

Prediction of Aerodynamic Noise for Centrifugal Fan of Air-Conditioner by Tetra-Prism Grids

We calculated fan performance and aerodynamic noise in the centrifugal fan of air conditioner by large eddy simulation (LES). In this study, we investigated simulation technology employing tetra-prism grids for practical usefulness. Tetraprism grids are easier to generate than hexahedral grids. We employed the numerical simulation code FrontFlow/blue (FFB) throughout the LES. First, we proposed a design method for tetra-prism grids. The design method featured a predicted boundary layer thickness that was the same as the thickness of a prism layer. Next, we compared calculated results for the 13 million grids, 107 million grids and 860 million grids to investigate the grid number influence on fan performance and aerodynamic noise. We confirmed that calculated results for larger number of grids was more accurate than smaller number of grids. We also confirmed that calculated results simulated streaks well and the number of streaks increased in the order of the increasing number of the grids. The proper simulating of the streaks therefore contributed to getting better calculated results. As a result, we confirmed that using the tetra-prism grids was practical in the actual development of fans.

Strategies to Minimise Numerical Ventilation in CFD Simulations of High-Speed Planing Hulls

Numerical Ventilation (NV) is a well-known problem that occurs when the Volume of Fluid method is used to model vessels with a bow that creates a small, acute entrance angle with the free surface. These are typical of both planing hulls and yachts. There is a general lack of discussion focusing upon Numerical Ventilation available within the public domain, which is attributable to the fact that it only affects such a niche area of naval architecture. The information available is difficult to find, often fleetingly mentioned in papers with a different focus. Numerical Ventilation may be considered one of the main sources of error in numerical simulations of planing hulls and as such warrants an in-depth analysis. This paper sets out to bring together the available work, as well as performing its own investigation into the problem to develop a better understanding of Numerical Ventilation and present alternate solutions. Additionally, the success and impact of different approaches is presented in an attempt to help other researchers avoid and correct for Numerical Ventilation. Interface smearing caused by the simulations inability to track the free surface is identified as the main source of Numerical Ventilation. This originates from the interface between the volume mesh and the prism layer mesh. This study looks into the interface to identify strategies that minimise Numerical Ventilation, presenting a novel solution to prism layer meshing that was found to have a positive impact. Through the implementation of a modified High Resolution Interface Capture (HRIC) scheme and the correct mesh refinements, it is possible to minimise the impact of Numerical Ventilation to a level that will not affect the results of a simulation and is acceptable for engineering applications.

Thorough Verification and Validation of CFD Prediction of FPSO Wind Load for Confident Applications

This paper presents our verification work on CFD modeling practice for the prediction of FPSO wind loads. The modeling practice was developed from the TESK CFD JDP [1]. In the verification, the measured data from a benchmark model test were used to check CFD simulation results. The exact physical model of the model test was used in the numerical modeling (model-of-the-model). To establish high confidence in the CFD modeling and simulations, the modeling practice was thoroughly verified, which covered the following critical elements: mesh resolution, domain size, outlet boundary condition, turbulence model, Reynolds effect, wind profile, prism layer effect on total wind forces, effects of the gap between wind tunnel floor and model bottom, blockage effect due to tunnel side walls and ceiling, and effects of geometry details (small size pipes). The verification results show that CFD can be used as an alternative tool for predicting wind loads and moments on a FPSO for engineering purposes following the modeling practice, and careful QA and QC.

Numerical Simulation of Crud Effects on the Flow and Heat Transfer Performance in PWR 17×17 Rod Bundles

Corrosion products on fuel cladding surface have a significant impact on reactor operation. These types of deposits are defined as Corrosion Residual Unidentified Deposit (CRUD) and are consist of a porous matrix of nickel and iron based oxides deposited on the fuel cladding surface. It is well known that crud deposits may cause potential Crud Induced Localized Corrosion (CILC) risk and Crud Induced Power Shift (CIPS) risk. The paper presents a Computational Fluid Dynamic (CFD) method of predicting the crud effect on the thermal hydraulic performance. The effect of the crud roughness is mainly considered in the simulation, the flow near the wall of the crud is solved by modifying wall function in the prism layer. The simulation object is a span of typical 17×17 rod bundle with a mid grid in PWR, all the structures including grid straps, springs, dimples, mixing vanes and welding spots are included. Thicknesses of grid and fuel cladding are considered in order to precisely simulate the fluid-solid conjugate heat transfer. The crud is set to be covered on the full span downstream of the grid. The simulation is based on the CILC risk pre-analysis and the computed information in the mostly likely crud deposit position is used as boundary condition. Based on the simulation results, the crud effects on the flow characteristics including vortex structures, circulation, turbulent intensity and second flow intensity and the heat transfer characteristics including rod temperature, fluid temperature and heat transfer coefficient are discussed in detail.