CFD studies of complex fluid flows in pipes

The flow of rheologically complex fluids in industrial equipment poses a number of challenges, not least from a modelling point of view. Research is needed to further understand and be able to predict the flow behaviour of such materials and to investigate ways of improving their processing. This work investigates the numerical modelling of complex fluids in three areas: flow and heat transfer under an externally imposed mechanical vibration, and steady-state solid-liquid flows as a first step in extending the vibration studies to these multiphase systems. Validated CFD simulations were used to study the effects of rotational and transversal mechanical vibrations on the pipe flow of viscous non-Newtonian fluids of the power-law, Bingham plastic, and Herschel-Bulkley types. Vibration frequencies in the sonic range of 0-300 Hz and linear amplitudes of 0-4 mm were used. The results showed that rotational and transversal vibrations give rise to substantial enhancements in flow for shear thinning and viscoplastic fluids, while shear thickening fluids experienced flow retardation. The flow enhancement was found to depend on vibration frequency and amplitude, fluid rheological properties, and pressure gradient. These vibrations can be effective at enhancing the flow of low to moderately viscous fluids in industries such as the confectionery industry. For extremely viscous fluids (consistency index ~10 kPa s$^n$ and yield stress ~200 kPa), ultrasonic frequencies (> 16 kHz) were found to produce orders of magnitude enhancements in flow. These results suggest that vibration can increase the fluidity of highly viscous fluids in industrial applications such as polymer extrusion. Results are also reported for the effects of transversal vibration on heat transfer and temperature uniformity in Newtonian and non-Newtonian shear thinning fluids. Vibration was found to generate sufficient chaotic fluid motion that led to considerable radial mixing which translated into a large enhancement in wall heat transfer as well as a near-uniform radial temperature field. Vibration also caused the temperature profile to develop very rapidly in the axial direction, thus, reducing the thermal entrance length by a large factor, so that much shorter pipes can be used to achieve a desired exit temperature. These effects increased with both vibration frequency and amplitude but were more sensitive to the amplitude. Higher fluid viscosities required larger amplitudes and/or frequencies to achieve substantial temperature uniformity. These results have significant implications for processes where a wide temperature distribution over the pipe cross-section is undesirable as it leads to an uneven distribution of fluid heat treatment, such as in the thermal sterilisation of food products. A numerical study was also conducted of the laminar pipe transport of coarse spherical particles (d = 2-9 mm) in non-Newtonian carrier fluids of the power law type using an Eulerian-Eulerian CFD model. The predicted flow fields were validated by PEPT experimental measurements of particle velocity profiles and passage times, whilst solid-liquid pressure drop was validated using relevant correlations gleaned from the literature. The study was concerned with nearly-neutrally buoyant particles (density ~1020 kg m$^{-3}$) flowing in a horizontal or vertical pipe at concentrations up to 40% v/v. The effects of various parameters on the flow properties of such mixtures were investigated over a wide range of conditions. Whilst the effects of varying the power law parameters and the mixture flow rate for shear thinning fluids were relatively small over the range of values considered, particle size and concentration had a significant bearing on the flow regime, the uniformity of the normalised particle radial distribution, the normalised velocity profiles of both phases, and the magnitude of the solid-liquid pressure drop. The maximum particle velocity was always significantly less than twice the mean flow velocity for shear thinning fluids, but it can exceed this value in shear thickening fluids. In vertical down-flow, particles were uniformly distributed over the pipe cross-section, and particle diameter and concentration had little effect on the normalised velocity and concentration profiles. Pressure drop, however, was greatly influenced by particle concentration. These results can help in understanding and predicting the flow behaviour of such solidliquid mixtures in industrial applications, such as the conveying of particulate food suspensions

Morgan- Voyce Approach for Solution Bratu Problems

Bratu equations are substantial in electrostatic and plasma problem. The aim of this paper is design a morgan-voyce approach for solving bratu problem. We present a morgan-voyce polynomial along with significant properties; the effectiveness of the proposed algorithm is demonstrated by considering three numerical examples

Effect of designed self-care educational program on anxiety, stress, and depression in patients with benign prostatic hyperplasia undergoing prostate surgery

BACKGROUND: Stress, anxiety, and depression are common psychological problems in prostatic conditions. The aim of this study was to investigate the effects of designed self-care educational program on anxiety, stress, and depression in patients with benign prostatic hyperplasia undergoing prostate surgery. METHODS: This was a quasi-experimental study including 33 participants in the intervention group and 34 participants in the control group. During the study demographic data and the rate of stress, anxiety, and depression were measured. In the intervention group, self-care educational program was presented in two sessions and was followed up one month after surgery. Stress, anxiety, and depression were measured before surgery, and during and one month after discharge using depression anxiety stress scales (DASS-21), which is a standard questionnaire. Later data were analyzed using SPSS software. RESULTS: Participants in the study were between 45-80 years of age. Student’s independent t-test before the intervention revealed no significant difference in mean score of stress (P = 0.684), anxiety (P = 0.937), and depression (P = 0.727) between the two groups. Mean score of stress and anxiety significantly reduced in the intervention group on discharge (stress: P = 0.031, anxiety: P = 0.043), and a month after the operation (stress: P ≤ 0.001, anxiety: P = 0.016). However, mean score of depression revealed no significant difference on discharge (P = 0.514), and a month after operation (P = 0.221). CONCLUSION: The results showed that designed self-care educational program was effective in stress and anxiety reduction in patients under prostate surgery

Silica fume concrete in hot and temperate environments

his investigation deals with the influence of hot and temperate curing environments on the hardened properties of concrete and mortar mixes. Condensed silica fume was blended with OPC as a potential alternative cementitious material to plain OPC for use in the hot Iraqi climate, in an attempt to find a cement combination that would overcome some of the durability problems experienced when using a plain OPC concrete in such an environment. Throughout the investigation two curing environments were used: the first simulating the UK temperate climate and the second simulating the hot Iraqi climate. Temperature and humidity were varied to simulate day and night time. The first stage of the experimental study was the development of a mix design method capable of producing an OPC-CSF cement concrete of a medium workability and a specific 28-days compressive strength ranging between 25 to 55 MPa, both with and without superplasticizer. Three grades of concrete strength were chosen (25,40 and 55 MPa) and the effect of four cement replacement levels (5,10,15 and 20%) of silica fume on concrete compressive strength was assessed. Test results showed that CSF was relatively more effective in lean mixes than in rich ones. Compressive strength of CSF concrete increased with increasing CSF percentages for both normal and superplasticized mixes up to an optimum levels of 10-15% and 15-20%, respectively. The amount of OPC (kg/m`3) necessary to bring a change in compressive strength of 1MPa was also determined and the theoritical blend proportions of OPC-CSF necessary to produce 28-day compressive strength equivalent to the plain OPC mixes were determined from the produced data above. The theoretical blend proportions were examined experimentally and the data were used to establish the relationship between strength and water/cementitious ratio for the blend mixes with and, without superplasticizer. Results showed that this basic relationship had changed quantitatively but not qualitatively when CSF was used. A cost study using current OPC and CSF material costs -was performed in an attempt to determine'the- most economic blend proportions. A total of eleven different concrete -mixes were selected to study the effect of curing environment (hot and temperate), initial curing time (0,1,3 and`-7 days) and curing method (water and polythene sheeting) on the compressive strength, permeability and absorption properties of the CSF concretes. Tests were carried out at 3,7, '14, 28,56,90 and 180 days of age. In addition five different mortar, mixes were used to examine the effect of curing environment (temperate and hot) an the *permeability, pore size distribution and durability to magnesium sulphate attack. Test results showed that hot Iraqi curing environment was favourable to the early-age strength, absorption and permeability of plain OPC mixes. However, - the later-age properties were significantly lower than those obtained for concretes cured in a temperate UK environment. For plain OPC mixes a critical curing period of 3 days was found under both temperate and hot environment. For the CSF blend mixes critical curing periods for the temperate and hot environment were found to be 3 and 1 day respectively. Results also reveal the importance of curing specimens immediately after casting for one day. Research work has also confirmed the superiority of water curing over polythene sheeting in a temperate environment for the rich plain OPC and CSF mixes. However, there was no significant difference between water and polythene for lean mixes. The reduction in , permeability and absorption properties of CSF mixes cured in a both temperate and hot environments is thought to be due to the changes in the pore structure brought about by the use of silica fume. Combining CSF with OPC was found to increase the percentages and volume of fine pores at the expense-of coarse pores. This effect may be described as a "refining" effect. Finally, the performance of CSF mortar mixes cured in a temperate and hot environment and their resistance to magnesium sulphate attack was significantly better than the plain OPC ones

Parental participation and mismanagement: a qualitative study of child care in Iran.

The purpose of this study was to explore parents' and nurses' experiences of parental participation in child care in hospitals in Iran. Using thematic analysis, the data were collected through interviewing 14 parents and 11 nurses from two pediatric hospitals. The results showed that four major themes emerged, including the necessity of a parent's presence, the unplanned and informal delegation of care to the parents (which itself had five subthemes: the parents as nurses, the delegation of care without sufficient and planned parental training, informal parent-to-parent support, the continuum of parents' willingness to participate, and the neglect of parents' needs), the inconsistency of care, and the parents as informal evaluators of care. Based on the study's findings, effective communication by nurses with parents is required. Nurses need to make an ongoing assessment of parents' wishes for involvement and negotiate care accordingly, with enough support and supervision to warrant quality of care

Slope line coding for telecommunication networks

A new slope line code for information transmission and storage has been proposed. The line code operates on the principle of slope coding. Two alternative slopes are used to transmit or store the binary information 1 s and 0 s. The decoder extracts the binary information from the received multilevel signal using slope comparison technique with slope violation detector from the incoming symbols. The encoder and decoder operation is described. A simulation of the encoder and decoder has been carried out using MultiSIM® software. The simulated results are in thorough agreement with the theory. The slope line code also meets the many desirable features of other line codes. This makes it attractive and suitable for data transmission and storage on different types of telecommunication networks and multimedia systems

Treatment of hyper-granulated limb wounds in horses

This study was performed to investigate the different methods of treating hyper granulation tissue on experimentally induced wounds in equine limbs. Wounds were induced by removal of a skin patch and subcutaneous tissue for about 5-7 cm width and 6-8 cm in length from the dorsal and lateral aspect of the fore and hind limbs below the carpal and tarsal joints. The wounds were left open without treatment and the animals were trained 2-2.5 hours every day for about 3-5 weeks until hyper granulation tissue was developed. The schedule for the treatment of hyper granulation was divided into five groups each contained eight wounds of hyper granulation tissue; each main group was divided into two subgroups. The subgroups of first, second, third, fourth and fifth groups were treated by the following schedules: bandage alone; copper sulphate ointment 10%; silver nitrate ointment 2%; red mercury ointment 11%; and laser therapy (at a total dose of 9.72 Joule / cm2) respectively. While the second subgroups were treated by surgical resection of the hyper granulation tissue, followed by the same treatments applied on the first subgroup. The bandage for all experimental groups was changed every 48 hours until healing was occurred. The clinical and histological observation of the first group revealed that the healing take long period comparing with other groups. The mean of wound healing were 65 days in non surgical removal of hyper granulation tissue subgroup, while 57 days in surgical removed of hyper granulation tissue subgroup. The results of the second, third, fourth groups revealed that the caustic material especially red mercury has a role in healing processes through depressing the hyper granulation tissue. The mean of wound healing of the second group was 42.25 days in non surgical removal of hyper granulation tissue subgroup while 37.25 days in surgically removed hyper granulation tissue subgroup. In the third group the mean of wound healing was 45.75 days in non surgical removal of hyper granulation tissue subgroup while 44.75 days in surgically removed hyper granulation tissue subgroup. While in the fourth group the mean of wound healing was 39 days in non surgical removal of hyper granulation tissue subgroup while 36 days in surgically removed hyper granulation tissue subgroup. In the fifth group the clinical and histological observation revealed that the using of laser lead to reduce the period for wound healing significantly comparing with other groups. The mean of wound healing was 25 days in non surgical removal of hyper granulation tissue subgroup while 20 days in surgically removed hyper granulation tissue subgroup, so that the laser was the best in this study and the using of surgical removal is better than of non surgical removal