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Home > Numerical Analysis of Flow Charateristics of Multiple Cylinders in Different Staggered Arrangements Using Lattice Boltzmann Method

Numerical Analysis of Flow Charateristics of Multiple Cylinders in Different Staggered Arrangements Using Lattice Boltzmann Method

Thesis Info

Access Option

External Link

Author

Nazeer, Ghazala

Program

PhD

Institute

COMSATS University Islamabad

City

Islamabad

Province

Islamabad.

Country

Pakistan

Thesis Completing Year

2018

Thesis Completion Status

Completed

Subject

Mathemaics

Language

English

Link

http://prr.hec.gov.pk/jspui/bitstream/123456789/12811/1/Thesis.pdf

Added

2021-02-17 19:49:13

Modified

2024-03-24 20:25:49

ARI ID

1676726772143

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Computational fluid dynamics (CFD) has become a powerful tool for solving complex fluid flow problems in the last few decades. The relation between the flow regime transformation and its corresponding hydrodynamics forces on the staggered cylinders has not been studied at low Reynolds number (Re), both experimentally and numerically. In order to do so, numerical investigations are conducted to study the unsteady flow past square cylinders arranged in staggered configurations. Six distinct staggered geometries are constructed for which simulations are carried out by using two dimensional single relaxation time lattice Boltzmann method (SRT-LBM). The combined effect of Re and separation ratio (g*) on the flow physics and hydrodynamics forces is systematically studied. For this study, physical parameters of practical importance are chosen in the range of 20 ≤ Re ≤ 160 and 0 ≤ g* ≤ 7. The SRT-LBM was validated by comparing the unsteady flow around an isolated cylinder and two cylinders with available experimental and numerical data. Results are presented in the form of instantaneous vorticity contour visualization, time-histories of drag and lift forces, power spectra of lift signals and hydrodynamic forces. For all chosen geometries critical spacing ratio and Reynolds number are identified. It is observed that with increase in spacing ratios between the cylinders the critical Reynolds number for the onset of vortex shedding phenomena also increases. Different flow regimes are observed for different staggered geometries. Chaotic flow is one of the common flow regime. The transformation of the flow occurs due to the interaction between primary and secondary frequencies; the latter frequency strongly depends on the spacing ratio between cylinders. The effect of jet flows on the wake structure mechanism (shed vortices) behind the cylinders is studied in detail. The results show that both Re and g* have a significant effect on the hydrodynamic forces. The flow regime maps for varying Re and g* are proposed for all considered problems. All these results, most of which have been obtained for the very first time, are of fundamental significance in engineering applications.
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منشی محمد احتشام علی کاکوروی

منشی محمد احتشام علی کاکوروی 
لکھنؤ کی سرزمین میں اپریل کے چوتھے ہفتہ میں ایک اور حادثہ پیش آیا یعنی کاکوری کے ممتاز خاندان کے رئیس جناب منشی محمد احتشام علی صاحب نے ۲۲؍ اپریل کی صبح کو ۷۵ برس کی عمر میں وفات پائی، کہنا چاہئے کہ اودھ میں قدیم شریفانہ جوہر وضعداری، دینداری، مروت، سیرچشمی، غربا نوازی اور مسکین پروری کا یہ اخیر نمونہ تھا، ان کی پوری زندگی میں جس میں وسعت کا زمانہ بھی تھا اور تنگی کا بھی، ان کے ہاتھ یکساں کھلے رہے اور اس اخفاء کے ساتھ کہ بائیں ہاتھ کو بھی داہنے ہاتھ کی خبر نہ تھی، وہ مولانا شاہ فضل رحمان صاحب گنج مراد آبادی سے بیعت تھے، اس تعلق کو اخیر اخیر وقت تک جس طرح نباہا، وہ ان کی سعادت مندی کا نشان ہے، پابندی یہ کہ مرتے وقت سجدہ عبودیت ادا کیا ہے اور صبر و شکر کے کلمے زبان سے نکلتے رہے۔
ان کی جوانی تھی کہ ندوۃ العلماء کا غلغلہ بلند ہوا، چونکہ اس مجلس کے سرپر فضل رحمانی سایہ فگن تھا۔ اس لئے حضرت شیخ کے سارے حلقہ بگوش اس کے حلقہ میں تھے اور اسی مناسبت سے جناب منشی محمد اطہر علی صاحب مرحوم اور ان کے ساتھ میں جناب منشی احتشام علی صاحب ندوہ کے خدام میں داخل ہوئے تھے، اپریل ۱۸۹۵؁ء میں اس کا پہلا جلسہ لکھنؤ میں ہوا تھا، اس اپریل ۱۸۹۵؁ء سے لے کر ۲۲؍ اپریل ۱۹۴۳؁ء کی صبح تک جب کہ انہوں نے زندگی کی اخیر سانس لی ہے، یکساں دلچسپی خلوص و انہماک سے اپنے فرائض کو انجام دیا ہے۔ نہ صرف رئیسوں میں بلکہ مسلمانوں میں اس قدامت خدمت اور مخلصانہ مذہبی خدمت گزاری کی مثال شائد ہی ملے۔
خیالی گنج میں ان کی بڑی اور وسیع کوٹھی، ان کے عزیزوں کا...

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