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Heat and Mass Transfer in Hydromagnetic Flows of Viscous Fluids over a Flat Plate

Thesis Info

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Author

Shah, Nehad Ali

Program

PhD

Institute

Government College University

City

Lahore

Province

Punjab

Country

Pakistan

Thesis Completing Year

2019

Thesis Completion Status

Completed

Subject

Mathemaics

Language

English

Link

http://prr.hec.gov.pk/jspui/bitstream/123456789/12712/1/Nehad%20Ali%20Shah%20PhD%20Thesis.pdf

Added

2021-02-17 19:49:13

Modified

2024-03-24 20:25:49

ARI ID

1676726361680

Similar


In the present thesis, we have presented the analytical studies of some fluid flow models. We wish to investigate three main problems. In this regard, we study the Stocks’ second problem taking to account porous and magnetic effects. General ex- pressions for the velocity and shear stress fields and the skin friction coefficient cor- responding to the motion due to a moving plate is used to provide new interesting solutions for the second problem of Stokes. As an application, exact solutions are developed for motions induced by an arbitrary time dependent shear stress on the boundary. Next, we have investigated the problem of hydromagnetic free convec- tion flow over a moving infinite vertical plate with Newtonian heating, mass diffusion and chemical reaction in the presence of a heat source. Radiative and porous effects are not taken into consideration but they can be immediately included by a sim- ple rescaling of Prandtl number and magnetic parameter. Exact general solutions for the velocity and concentration fields, the corresponding Sherwood number and skin friction coefficient are determined under integral form in terms of error function or complementary error function of Gauss. Moreover, for illustration, three special cases are considered and the influence of physical parameters on some fundamental motions are graphically underlined and discussed. The required time to reach the steady-state for cosine or sine oscillating concentrations on the boundary is graphi- cally determined. The presence of destructive chemical reaction is improved this time for increasing values of chemical reaction parameter. Finally, we have investigated the hydromagnetic natural convection flow of an electrically conducting, incompressible viscous fluid over a moving infinite, vertical plate with exponential heating, chemical reaction and constant concentration. Radiative effects are also taken into considera- tion in the presence of transverse magnetic field that is either fixed to the fluid or to the plate. The dimensionless velocity, as well as the corresponding skin friction, are presented as sum of mechanical, thermal or concentration components whose contri- bution to the fluid motion are graphically brought to light for motions due to slowly accelerating translations of the plate. Moreover, steady-state solutions corresponding to motions due to cosine or sine oscillations of the plate are presented in simple and el- egant forms and the required time to reach the steady-state is graphically determined and discussed.
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مولانا ابوبکر اصلاحی

مولانا ابوبکر اصلاحی
افسوس ہے کہ ۲؍ مئی کو جماعت اسلامی کے ایک ذمہ دار بزرگ اور اعظم گڑھ کے اطراف کے مشہور عالم مولانا ابوبکر اصلاحی صاحب نے داعی اجل کو لبیک کہا، مدرسۃ الاصلاح سے فراغت کے بعد انہوں نے ضلع بستی میں دینی تعلیم کی اشاعت اور درس و تدریس کی خدمت انجام دی، ۴۶؁ء میں مدرسۃ الاصلاح آئے۔ راقم نے صرف و نحو اور فقہ کی بعض کتابیں ان سے پڑھیں، وہ جماعت کے بڑے سرگرم رکن تھے، اس لیے مدرسہ سے سبکدوش ہوکر اس کے تنظیمی کاموں میں لگ گئے، ان کی اچھی کارگزاری کی بنا پر جب جامعۃ الفلاح قائم ہوا تو اس کی ترقی و استحکام کا کام انہیں سپرد کیا گیا اور وہ عرصہ تک اس کے نیک نام ناظم و صدر مدرس رہے۔ اب علالت و معذوری کی وجہ سے سرائمیر میں اپنے گھر ہی رہتے تھے۔
دارالمصنفین بھی تشریف لاتے تھے، مولانا شاہ معین الدین احمد ندوی سے تعلق خاطر تھا۔ مولانا ابوبکر صاحب کی وفات سے جماعت اسلامی اپنے ایک اچھے اور مخلص کارکن سے محروم ہوگئی، اﷲ تعالیٰ مغفرت فرمائے اور پس ماندگان کو صبر جمیل عطا کرے۔ آمین! (ضیاء الدین اصلاحی، مئی ۱۹۹۸ء)

 

اﻷداء اﻟﻤﺄﻣﻮر ﺑﻪ و ﺗﻄﺒﻴﻘﺎﺗﻪ اﻟﻔﻘﻬﻴﺔ

In the Islamic Law i. E. Quran and Sunnah the above mentioned topic has been discussed clearly and repeatedly to avoid any ambiguity in dealings in our daily life and agreements made between two parties or governments national or international levels. After intensive study I discussed and elaborated the said issue referring to the Qura’nic verses and sayings of the Prophet (SAW). The matter is of great importance; hence the Muslims Jurists have also given their valuable opinions in accordance with the Islamic Law which have been incorporated also to solve the issue. If we act upon these verdicts, we will be able to select the best among ourselves and form an ideal government and will discharge our duties honestly, and eventually our every act will show our responsibility to perform our duties and to give due share to the right person.

Preparation and Functionalization of Waste Tea Derived Carbon for Adsorption of Cationic Dyes from Equeous Solutions.

Low cost and eco-friendly activated carbon (AC) was prepared from a cheap precursor material, used tea leaves (UTLs), by chemical activation with phosphoric acid (PA) under optimum conditions, using central composite design (CCD) of response surface methodology (RSM). The conditions optimized were activation temperature, chemical impregnation ratio (IR) and activation time with % age yield, iodine (I2) and methylene blue (MB) number as the targeted responses. The optimal preparation conditions were determined as: activation temperature of 600 oC, impregnation ratio (IR) of 1.30 and activation time of 130 min, under which a carbon yield of 33.55 % and I2 and MB uptake of 1051 mg g-1 and 321 mg g-1 respectively, could be achieved. The AC produced by phosphoric acid activation under optimal conditions (PA-AC) was subsequently modified with hydrogen peroxide and anionic surfactant, sodium dodecyl sulfate (SDS). The optimal (PA-AC), hydrogen peroxide (PA-AC-HO) and SDS modified carbons (PA-AC-SDS) were utilized for cationic dyes removal from aqueous medium.PA-AC, PA-AC-HO and PA-AC-SDS were characterized by various physio-chemical techniques including TG/DTA, SEM, XRD, FTIR spectroscopy, BET surface area, Boehm’s titration, pHPZC and proximate-ultimate analysis. Results showed that all the three adsorbents have sufficient number of acidic functional groups and their pHPZC values lies in the acidic region. The pHPZC values of PA-AC, PA-AC-HO and PA-AC-SDS were found to be 4.60, 3.40, and 5.20, respectively. Boehm’s titration results showed that PA-AC-HO surface has more acidic groups than PA-AC and PA-AC-SDS. TG/DTA analysis of the three samples showed very small weight loss in the temperature range 110-1000 oC indicating high carbon and low volatile matter content which is supported by EDX and proximate analysis results. XRD analysis showed the amorphous nature of the three samples.PA-AC has larger BET surface area and micropore volume than PA-AC-SDS and PA-AC-HO while, PA-AC-HO has greater fraction of mesopore volume (57.83 %). The SEM study confirmed that the external surface of raw UTLs is rough with few small pores while that of PA-AC, PA-AC-HO and PA-AC-SDS is highly porous with numerous cavities which make them suitable to adsorb cationic dyes from aqueous solutions. Pore widening and some cracks were also observed on PA-AC-HO surface with a corresponding BET surface area and micropore volume decrease. The SEM analysis also showed that after cationic dyes uptake most of the pores disappeared in all the three AC samples due to saturation with dyes molecules. xi To find the efficiency of the prepared adsorbents, all the three AC samples were utilized for the adsorption of five cationic dyes BB-9, BY-2, BB-41, BG-4 and BV-3 from aqueous mediums by studying different process parameters. The uptake of all these dyes by PA-AC, PA-AC-HO and PA-AC-SDS was low in the acidic pH range (pH 2.0-4.0) and increased with increasing pH of the solution beyond 4.0. Dyes uptake per unit mass of adsorbents was highly dependent on dyes initial concentrations, contact time, adsorbent dose, particle size and ionic strength. Kinetic data was analyzed using different models to explain the rate and mechanism of BB-9, BY-2, BB-41, BG-4 and BV-3 adsorption onto PA- AC, PA-AC-HO and PA-AC-SDS. The adsorption data was described by pseudo-second order kinetic model having high coefficients of correlation (R2 ˃ 0.99), and the qe calculated were in close agreement with the experimentally determined adsorption amount (qe, exp) for each cationic dye at all the studied concentrations. The rate constant k1 (min-1) values for PA-ACHO were higher than PA- AC and PA-AC-SDS. Intra-particle diffusion and Boyd’s models verified that during interaction of the dyes with PA-AC, PA-AC-HO and PA-AC-SDS both film diffusion and intra-particle diffusion may occur parallel. Langmuir and Temkin isotherms models explained the equilibrium adsorption data very well as evident from R2 values. The value of binding energy constant (KL) for all adsorbents were higher at high temperature, showed favorable adsorption of dyes at higher temperature. Moreover, the values of separation factor (RL) lies between 0 and 1, confirming that adsorption of BB-9, BY-2, BB-41, BG-4 and BV-3 onto PA-AC, PA-AC-HO and PA-AC-SDS can be described very well by Langmuir model. The positive ∆Ho values showed endothermic nature of BB-9, BY-2, BB-41, BG-4 and BV-3 adsorption onto PA-AC, PA-AC-HO and PA-AC-SDS. The positive ∆So values suggested increased randomness at solid/liquid interface during the adsorption process which reflects high affinity of these adsorbent for cationic dyes. The ∆Go values were negative at all the temperatures studied, suggesting spontaneous nature of dyes adsorption. In binary systems the individual dyes adsorption capacities [qe,i(mg g-1)] and adsorption yield [Adi,%] were smaller than those estimated for each dye in single component solution, showing antagonistic adsorption of dyes. Regeneration of dyes loaded adsorbents was carried out by five consecutive cycles. Results showed that PA-AC has good regeneration capacity, followed by PA-AC-SDS and PA-AC-HO. Subject Headings: Surface Chemistry, Material Chemistry, Environmental Chemistry, Advanced Instrumental Techniques, Statistical Optimaization Techniques, Chemical Kinetics, Thermodynamics, Ion Exchange, Dyes and Pigments, Environmental remediation