Entropy generation for forced convection in a porous saturated circular tube with uniform wall temperature

A numerical study is reported to investigate both the First and the Second Law of Thermodynamics for thermally developing forced convection in a circular tube filled by a saturated porous medium, with uniform wall temperature, and with the effects of viscous dissipation included. A theoretical analysis is also presented to study the problem for the asymptotic region applying the perturbation solution of the Brinkman momentum equation reported by Hooman and Kani [1]. Expressions are reported for the temperature profile, the Nusselt number, the Bejan number, and the dimensionless entropy generation rate in the asymptotic region. Numerical results are found to be in good agreement with theoretical counterparts

Entropy generation analysis of thermally developing forced convection in fluid-saturated porous medium

Entropy generation for thermally developing forced convection in a porous medium bounded by two isothermal parallel plates is investigated analytically on the basis of the Darcy flow model where the viscous dissipation effects had also been taken into account. A parametric study showed that decreasing the group parameter and the Péclet number increases the entropy generation while for the Brinkman number the converse is true. Heatline visualization technique is applied with an emphasis on B

PUFA content of silages prepared from tuna cannery wastes

Ensiling as one of the best methods for utilization of tuna wastes was investigated. docosahexaenoic acid [DHA C22:6(n-3)]- rich products were obtained from the wastes (viscera and dark meat) of four tuna species, namely longtail, skipjack, yellowfin and kawakawa by a procedure involving ensiling in organic acids followed by neutralization. Identification of fatty acids in the samples was performed by comparison with chromatograms of fatty acids standard. Total lipid content of silages varied from 10.41% in skipjack dark meat silage to 22.01% in kawakawa viscera silage, but all lipids contained high percentages of DHA and EPA [eicosapanteoneic acid C20:5(n-3)]. The highest DHA ratio (15% of total lipids) was found in the lipid of skipjack viscera silage and the highest ratio of EPA (11% of total lipids) belonged to the lipids of kawakawa dark meat silage. ANOVA test results indicated that DHA ratio was significantly high before silage preparation and linolenic acid [C18:3(n-3)] content significantly differed between the species (p<0.05)

Population dynamics of pearl oyster Pinctada radiata west of Lavan Island of the Persian Gulf, Iran

Investigation on pearl oyster, Pinctada radiata growth and mortality parameters was carried out from September 2001 to October 2002 in west of Lavan Island using scuba diving method. Hinge length (HL) and dorsoventral measurement (DVM) relationship was significantly (r ^ (2) =0.98) linear. Weight and dorsoventral measurement relationship was shown to be W=0.0004 L ^ (2.812) (r ^ (2) =0.98). Asymptotic length (L infinity) and growth rate (K) were estimated at 98 (mm) and 0.96 y ^ (-1) respectively. More than 70 percent of the individuals were matured in April 2001. Mortality parameters including natural mortality (M), total mortality (Z) and fishery mortality (F) were estimated to be 1.21y ^ (-1), 1.68y ^ (-1) and 0.66y ^ (-1) respectively. Exploitation rate was estimated to be 0.27 in this survey

Gracilaria corticata cultivation in fiberglass tanks and Agar extraction

In order to culture the G. corticata for further agar extraction, during one year study (2001), 3 treatments with 3 different densities of 500, 1000 and 2000 g/m^2 and 3 replicates were cultured in fiberglass tanks. During the culture period the parameters of temperature, pH and salinity were measured and 30-40 percent of water was exchanged once every two days. The aeration activity was constantly done and also 0.5g urea added into the water after exchanging the water. The biometric measurement of algae was carried out every week and ultimately end of the period culture, the daily growth and net production (wet weight) was calculated in proportion to g/m2. Also, amount of extracted agar (dry weight) estimated seasonally. In winter, the daily growth (%), net production and agar extracted (%) were estimated 1.46±0.11, 11.5±3.57 and 17.5%, in which these figures for three other seasons of spring, summer and autumn were: 3.74±0.31, 38.3±5.4, 19.3 and 1.5±0.28, 12.43±3.3, 14% and 3.11±0.04, 26.9±0.61 and 15%, respectively. Some epiphytes and grazers were recognized in algae cultivation tanks such as Navicula, Nitzschia, Oscillatoria, Peridinium, Chaetoceros, Enteromorpha, Ulva, and Isopoda, Nemertine and Nereis. Two seasons of spring and autumn showed the best daily growth and net production, and also the 500 g/m^2 treatment was recognized the best culture treatment

Comments on “Flow, thermal, and entropy generation characteristics inside a porous channel with viscous dissipation” by S. Mahmud and R.A. Fraser [Int. J. Thermal Sciences 44 (2005) 21–32]

Hoomen, Merrikh and Ejlali presents comment on the paper on 'Flow, thermal, and entropy generation characteristics inside a porous channel with viscous dissipation' by S. Mahmud and R.A. Fraser. The paper presents closed form solutions to the velocity and temperature distributions that would be very useful for checking numerical computations. The authors have applied the fluid thermal conductivity kf in all of the equations, that should be replaced by the effective thermal conductivity. They have presented the temperature distribution and the Nusselt number as a function of the Darcy number only, inspite of the fact that Re, Pr, and Ec will affect the temperature profile. The authors have applied a clear-fluid compatible term in the entropy production term that has not been already considered in the thermal energy equation. The reliability of the numerical results is questionable though the authors have applied a previously tested numerical scheme

Hydrodynamic modeling of traffic jams in intracellular transport in axons

Irregularities in intracellular traffic in axons caused by mutations of molecular motors may lead to “traffic jams”, which often result in swelling of axons causing such neurodegenerative diseases as Alzheimer’s disease and Down syndrome. Hence, it is of particular interest to mathematically model the formation of traffic jams in axons. This paper adopts the hydrodynamic continuity equations for intracellular transport of organelles as developed by Smith and Simmons [1] whereas the Kerner and Konhäuser [2] model for traffic jams in highway traffic is applied to predict the velocity field. It is observed that combination of the two sets of equations can comprehensively predict the traffic jams in axons without the need to any additional assumption or modification

Hydrology and hydrobiological monitoring in the northeastern part of the Persian Gulf and Strait of Hormoz (Hormozgan Province water)

Hydrology and Hydro-biological monitoring in the Northeast Persian Gulf and strait of Hormuz (Hormozgan Province waters) were conducted during 2003-2004.The project was implemented using R/V Ferdous.The sampling area included the stretch of the Iranian waters along the northeast part of the Persian Gulf and Strait of Hormuz in Hormuzgan province. Along this stretch 7 equally distributed transect at a distance of 40 miles from one another were designated; 3 main sampling stations at a distance of 20 miles from one another were fixed at each transect. Sampling was conducted twice per annun from Feb. 2003 to Feb. 2004. Summer & winter values of some Physico-chemical factors in surface layers of Hormozgan waters were recorded as follows: Temprature 33±0.082 , 21.8±0.67 ?c ; EC 66.1±1.52 , 53.3±0.66ms/cm ; Salinity 37.9±0.54, 37.8±1.6 ppt , Density 22.9±0.39 , 25.5±0.99 kg/m^3, Dissolved oxygen 5.4±0.26 , 6.7±0.35 ppm ; pH 8.2±0.02 , 8±0.03 ; chlorophyll-a 0.7±0.4 , 1.3±0.72 mg/m^3 and Turbidity 6.1±0.92 , 5.7±0.67 FTU. According to the result a seasonal thermocline appears in the Iranian waters during summer and disappear during winter, extended with its maximum formation in summer. The temperature differences between surface and bottom waters was 12?C. The thermocline diminishes near the Strait of Hormuz area, horizontal and vertical distribution recorded. Increase in salinity and density from northeast towards northwest and from surface to depth. Electrical conductivity depends on temperature in summer but in winter depend on salinity. Dissolved oxygen was higher in the layer of 5-20m and decrease with increasing depth. Maximum chlorophyll-a was recorded in layers of 10-30m and 5-20m in summer and winter respectively. The density of nutrients increase from surface to depth but decrease from northeast towards northwest and density of nutrients in winter was higher than summer show write how much. Plankton population in this study characterized by 4 phylum and 5 classes of phytoplankton, 6 phylum and 8 classes of zooplankton and 23 family of Ichthyoplankton. Total 63 spices of phytoplankton belonging to 43 Bacillariophyceae, 14 Dinophyceae, 4 Cyanophycea, one Chrysophycea and one Euglenaphycea. Bacillariophyceae inparticular show very high density in winter 83 and Euglenaphycea is dominant group only in winter. Crustaceans were the most dominant group of zooplankton. Calanoids and Cyclopoids were abundant at all stations. Zooplankton were increase from East to West. Among Ichthyplankton, Clupeeiidae family the most abundant, the Gobiidae was in second position and followed by Engrauliide with high density than other family. All together 124 genera belong to 132 families of macro-benthos were identified. As they consist of 59 genera belong to 49 families of Polychaete, 27 genera belong to 44 families of gastropod, 23 genera belong to 27 families of Bivalve, 15 genera belong to 10 families and 2 order of Crustacean and 2 families of Scaphopoda. Additionally some groups of Echiurida, Sipunculida , platyhelminenthes, Echinodermata, Foraminiferans, Cnideriars,Chordata, Cheatognatha and Lophophora were identified. The most dominant groups were Crustacean and Polychaetes in percentage of abundance proportion of studies in last years .The mean biomass of macrobenthos has been decreased to 4.7 g/m. Note: Some species of macro-benthos identified up to famil

Estimation of biomass and optimum of shrimp fishing season in Hormuzgan Province

This project was designed with for objective on estimation of Biomass and optimum time for catch season of P.merguinsis and M.affinis shrimps. This investigation was carried out monthly by swept area method in coastal waters of Hormozgan province. The optimum time for fishing season in Bandar Abbas to Sirik waters in 2004,2005 and 2006 respectively was about 25/9/2004, 24/9/2005 and 25/9/2006. Total allowable catch (T.A.C.) for P.merguiensis and M.affinis estimated in 2004 to 2006 were 600, 170 tonnes, 850, 550 tonnes and 650, 400 tonnes respectively. The densest catch was obtained for P.merguiensis (from 58/5 to 65/5 %) and the least catch for P.indicus (from 0/04 to 1/1 % ), respectievly

Environmental impacts of shrimp farms on coastal waters in Tiab area, Hormozgan province, south of Iran

Shrimp farming industry has rapidly expanded in the south of Iran and in particular in Honnozgan Province along the coastal line during the past decade. A survey was conducted for evaluation of environmental impacts of effluents from the shrimp farms during culture season (July-December 2003) of Tiab area in Hormozgan Province. The physicochemical parameters such as air and water temperature, salinity, pH, dissolved oxygen, BOD5, nitrite, nitrate, total ammonia, inorganic phosphorus and total phosphorus were recorded monthly from 9 stations. The stations consisted of two inlets (stations 13 3), two outlets of effluents (stations 2, 4) and the remaining 5 stations were located along the coastal lines. The parameters were measured at 21-40°C, 22on39°C, 37-54ppt, 7.85-8.38, 4-8.1mg/L, 0.2-8.5mg/L, 0.11-0 .186mg/L, 0.001-0.029mg/L, 0- 0.016mg/L, Ome0.043mg/L and 0.014-1.4mg/L) respectively. The results showed that the range of most of the measured parameters such as water temperature, salinity, BOD5, ammonia, nitrate, phosphate and TP in the outflow waters (2, 4) were higher than inflow (1, 3) and coastal waters (5, 6, 7, 8 ,9). Statistical analysis of variance (ANOVA) demonstrated a significant difference between outlet effluent and other stations (P<0.05). We also concluded that the nutrients in the culture effluents are somewhat used by fauna of the Tiab creek, hence decreasing the pollutant load of the effluent