Numerical Study on the Hydrodynamic Performance of Antifouling Paints

This study presents a simple numerical method that can be used to evaluate the hydrodynamic performances of antifouling paints.Steady Reynolds-averaged Navier-Stokes equations were solved through a finite volume technique,whereas roughness was modeled with experimentally determined roughness functions.First,the methodology was validated with previous experimental studies with a flat plate.Second,flow around the Kriso Container Ship was examined.Lastly,full-scale results were predicted using Granville’s similarity law.Results indicated that roughness has a similar effect on the viscous pressure resistance and frictional resistance around a Reynolds number of 10^7.Moreover,the increase in frictional resistance due to roughness was calculated to be approximately 3%-5%at the ship scale depending on the paint.

SYNTHESIS,CHARACTERIZATION,THERMAL DEGRADATION AND ELECTRICAL CONDUCTIVITY OF OLIGO[2-(2-HYDROXYPHENYLIMINOMETHYLBENZYLIDENE)AMINOPHENOL]AND OLIGOMER-METAL COMPLEXES

The oxidative polycondensation reaction conditions of 2-[(2-hydroxyphenyliminomethylbenzylidene)amino- phenol](2-HPIMBAP)has been accomplished by using air O_2 and NaOCl oxidants in an aqueous alkaline medium between 50-90℃.The optimum reaction conditions of the oxidative polycondensation and the main parameters of the process were established.At the optimum reaction conditions,yield of the products were found to be 67.72% and 61.49% for air O_2 and NaOCl oxidants respectively.The structures of the monomer ...

Numerical Investigation of the Effect of Surface Roughness on the Viscous Resistance Components of Surface Ships

Recently,computational fluid dynamics(CFD)approaches have been effectively used by researchers to calculate the resistance characteristics of ships that have rough outer surfaces.These approaches are mainly based on modifying wall functions using experimentally pre-determined roughness functions.Although several recent studies have shown that CFD can be an effective tool to calculate resistance components of ships for different roughness conditions,most of these studies were performed using the same ship geometry(KRISO Container Ship).Thus,the effect of ship geometry on the resistance characteristics of rough hull surfaces is worth investigating.In this study,viscous resistance components of four different ships are calculated for different roughness conditions.First,flat plate simulations are performed using a previous experimental study for comparison purposes.Then,the viscous resistance components of three-dimensional hulls are calculated.All simulations are performed using two different turbulence models to investigate the effect of the turbulence model on the results.An examination of the distributions of the local skin friction coefficients of the DTMB 5415 and Series 60 showed that the plumpness of the bow form has a significant effect on the increase in frictional resistance with increasing roughness.Another significant finding of the study is that viscous pressure resistance is directly affected by the surface roughness.For all geometries,viscous pressure resistances showed a significant increase for highly rough surfaces.

Combined Effects of Dietary Bacillus subtilis and Trans-cinnamic Acid on Growth Performance,Whole Body Compositions,Digestive Enzymes and Intestinal bacteria in Rainbow Trout(Oncorhynchus mykiss)

In this study,the combined effects of dietary Bacillus subtilis(BS,107 g/cfu)and different levels(0.025%,0.050%,0.075%and 0.150%)of trans-cinnamic acid(CA)on fish growth performance,whole body compositions,digestive enzymes,intestinal bacteria and internal organ index of rainbow trout(Oncorhynchus mykiss)were investigated.Six different experimental groups including control group(C),C+BS,0.025%CA+BS,0.050%CA+BS,0.075CA+BS,0.150%CA+BS)were established.According to the results obtained,growth performance,whole body compositions and digestive pH were not statistically significant among groups.Further,no significant differences were found between experimental groups in terms of the intestinal enzymes(trypsin,alkaline phosphatase and lipase)and gastric pepsin.Significantly higher levels of intestinal amylase were found in the control+BS,0.025%CA+BS,0.050%CA+BS,and 0.075%CA+BS compared to the control and 0.150%CA+BS groups.Moreover,coliform and Enterobacteriaceae counts were highest in the control+B.subtilis and lowest in the 0.150%CA+B.subtilis groups.