scholarly journals Towards a Computational Fluid Dynamics-Based Fuzzy Logic Controller of the Optimum Windcatcher Internal Design for Efficient Natural Ventilation in Buildings

2021 ◽  
Vol 2021 ◽  
pp. 1-10
Author(s):  
Ashraf Balabel ◽  
Mohammad Faizan ◽  
Ali Alzaed
Keyword(s):  
Fluid Dynamics ◽  
Computational Fluid Dynamics ◽  
Turbulence Model ◽  
Fuzzy System ◽  
Natural Ventilation ◽  
Experimental Measurements ◽  
Proposed Model ◽  
Engineering Problems ◽  
Ventilation Performance ◽  
Omega Model

Recently, increased attention has been given to the coupling of computational fluid dynamics (CFD) with the fuzzy logic control system for obtaining the optimum prediction of many complex engineering problems. The data provided to the fuzzy system can be obtained from the accurate computational fluid dynamics of such engineering problems. Windcatcher performance to achieve thermal comfort conditions in buildings, especially in hot climate regions, is considered as one such complex problem. Windcatchers can be used as natural ventilation and passive cooling systems in arid and windy regions in Saudi Arabia. Such systems can be considered as the optimum solution for energy-saving and obtaining thermal comfort in residential buildings in such regions. In the present paper, three-dimensional numerical simulations for a newly-developed windcatcher model have been performed using ANSYS FLUENT-14 software. The adopted numerical algorithm is first validated against previous experimental measurements for pressure coefficient distribution. Different turbulence models have been firstly applied in the numerical simulations, namely, standard k-epsilon model (1st and 2nd order), standard Wilcox k-omega model (1st and 2nd order), and SST k-omega model. In order to assess the accuracy of each turbulence model in obtaining the performance of the proposed model of the windcatcher system, it is found that the second order k-epsilon turbulence model gave the best results when compared with the previous experimental measurements. A new windcatcher internal design is proposed to enhance the ventilation performance. The fluid dynamics characteristics of the proposed model are presented, and the ventilation performance of the present model is estimated. The numerical velocity profiles showed good agreement with the experimental measurements for the turbulence model. The obtained results have shown that the second order k-epsilon turbulence can predict the different important parameters of the windcatcher model. Moreover, the coupling algorithm of CFD and the fuzzy system for obtaining the optimum operating parameters of the windcatcher design are described.

EVALUASI PERFORMA VENTILASI ALAMI PADA DESAIN BUKAAN RUANG KELAS UNIVERSITAS ATMA JAYA YOGYAKARTA

2017 ◽  
Vol 10 (3) ◽  
pp. 149
Author(s):  
Jackobus Ade Prasetya Seputra
Keyword(s):  
Fluid Dynamics ◽  
Computational Fluid Dynamics ◽  
Teaching And Learning ◽  
Natural Ventilation ◽  
Vertical Section ◽  
Case Study Research ◽  
Bottom Layer ◽  
Simulation Software ◽  
Windward Side ◽  
Ventilation Performance

Abstract: Education is an important sector of a nation toward better future. Conducive classroom with well designed room ventilation would encourage occupants in implementing effective teaching and learning activities. Research was conducted to figure out classroom performance and optimization of natural ventilation which was occurred in Engineering Faculty of UAJY represented by the classroom number 2406 as case study. Research is focused on classroom ventilation elements by examining window’s dimension, occupant’s adaptive behavior, opening types, and glass type at windward side. This research implements rationalistic method by utilizing computer simulation software DesignBuilder complemented with CFD in order to analyze and deduce information obtained primarily by field measurement and other relevant literatures. Results generated by DesignBuilder show that changes in ventilation area at external windows have significant influence over room’s ventilation performance. CFD (Computational Fluid Dynamics) experiments were conducted by examining opening types shown on room’s vertical section drawing, opening positions, overhangs, and external louvre types. Results show that experiments conducted by replacing the bottom layer of fixed windows with operable windows has significant effect in improving ventilation performance. Variation on overhangs only produce little impact, yet experiments on external louvres prove that the best type is horizontal louvre. Optimization done by studying above variables is capable to increase ventilation performance up to 800% in examined classroom.Keywords: ventilation, optimization, room openings, computer simulationAbstrak: Sektor pendidikan adalah tulang punggung suatu bangsa demi menuju masa depan yang lebih baik. Ruang kelas yang berkualitas dan kondusif dengan perencanaan sistem ventilasi dalam ruang yang baik bagi kegiatan belajar mengajar akan membantu tercapainya tujuan tersebut. Penelitian ini dilakukan untuk mengetahui sejauh mana performa ventilasi alami ruang dengan studi kasus Ruang Kelas 2406 Gedung Fakultas Teknik UAJY dan bagaimana bentuk optimasinya. Penelitian berfokus pada elemen bukaan dengan berbagai dimensi jendela, pengaturan adaptif penghuni, jenis bukaan ventilasi pada jendela, serta jenis kaca jendela pada sisi windward (angin datang). Metode simulasi komputer diperkuat dengan pengukuran lapangan menjadi alat bantu menakar dan mengoptimalisir kebutuhan ventilasi alami melalui berbagai variasi desain bukaan. Hasil studi dengan DesignBuilder memperlihatkan bahwa variabel luasan ventilasi pada jendela (“external window open”) memiliki pengaruh besar terhadap performa ventilasi alami dalam ruang. Studi dengan CFD (Computational Fluid Dynamics) berfokus pada model bukaan ruang, yaitu model bukaan pada potongan vertikal ruang, posisi bukaan, tipe teritisan (“overhang”) serta kerai (“louvre”) eksternal. Eksperimen pada posisi bukaan inlet menunjukkan bahwa perubahan jendela mati menjadi jendela hidup pada lapis bawah menghasilkan performa ventilasi lebih baik. Studi teritisan tidak memiliki pengaruh besar, sedangkan studi kerai membuktikan bahwa jenis kerai terbaik adalah kerai horisontal. Optimasi ini mampu meningkatkan performa ventilasi hingga 800% pada studi kasus.Kata kunci: ventilasi, optimasi, bukaan ruang, simulasi komputer

Numerical investigation of wind-driven natural ventilation performance in a multi-storey hospital by coupling indoor and outdoor airflow

2016 ◽  
Vol 25 (8) ◽  
pp. 1226-1247 ◽  
Author(s):  
Ruiqiu Jin ◽  
Jian Hang ◽  
Shanshan Liu ◽  
Jianjian Wei ◽  
Yang Liu ◽  
...  
Keyword(s):  
Fluid Dynamics ◽  
Computational Fluid Dynamics ◽  
Natural Ventilation ◽  
Tracer Gas ◽  
Indoor Airflow ◽  
Change Rate ◽  
Air Change Rate ◽  
Airflow Field ◽  
Ventilation Performance ◽  
Dynamics Simulations

This study employed two ventilation indexes: local mean age of air and air change rate per hour, to investigate wind-induced natural ventilation of 260 wards of a multi-storey hospital building in suburb of Guangzhou using computational fluid dynamics simulations. Using the surface-grid extrusion technique, high-quality hexahedral grid cells were generated for the coupled outdoor and indoor airflow field. Turbulence was solved by the renormalisation group k-ɛ model validated against experimental data with grid independence studies. Homogeneous tracer gas emission was adopted to predict room age of air. The air change rate of cross ventilation and single-sided ventilation can reach 30–160 h−1 and 0.5–7 h−1, respectively. Due to different locations of room openings on the balconies, natural ventilation of a room can be greatly better than its neighbouring room. The wind-induced cross ventilation highly depends on the distance from the room opening to the stagnation point and on the resulting pressure distribution on the target building surface. Furthermore, it is significantly influenced by the upstream buildings, the bent shape of the target building, and the prevailing wind directions. The coupled computational fluid dynamics methodologies with integrated ventilation indexes are useful for assessing the natural ventilation performance in other complex built environments.

Analysis of an Airfoil Using a Transition and Turbulence Model

2016 ◽  
Vol 819 ◽  
pp. 356-360
Author(s):  
Mazharul Islam ◽  
Jiří Fürst ◽  
David Wood ◽  
Farid Nasir Ani
Keyword(s):  
Fluid Dynamics ◽  
Boundary Layer ◽  
Computational Fluid Dynamics ◽  
Kinetic Energy ◽  
Turbulence Model ◽  
Original Version ◽  
Transitional Region ◽  
Cfd Analysis ◽  
Computational Fluid Dynamics Cfd

In order to evaluate the performance of airfoils with computational fluid dynamics (CFD) tools, modelling of transitional region in the boundary layer is very critical. Currently, there are several classes of transition-based turbulence model which are based on different methods. Among these, the k-kL- ω, which is a three equation turbulence model, is one of the prominent ones which is based on the concept of laminar kinetic energy. This model is phenomenological and has several advantageous features. Over the years, different researchers have attempted to modify the original version which was proposed by Walter and Cokljat in 2008 to enrich the modelling capability. In this article, a modified form of k-kL-ω transitional turbulence model has been used with the help of OpenFOAM for an investigative CFD analysis of a NACA 4-digit airfoil at range of angles of attack.

Tonal Noise Reduction in a Radial Fan With Forward-Curved Blades

2014 ◽  
Author(s):  
Manoochehr Darvish ◽  
Bastian Tietjen ◽  
Daniel Beck ◽  
Stefan Frank
Keyword(s):  
Fluid Dynamics ◽  
Computational Fluid Dynamics ◽  
Aerodynamic Performance ◽  
Computational Aeroacoustics ◽  
Experimental Measurements ◽  
Noise Generation ◽  
Tonal Noise ◽  
Outlet Angle ◽  
And Performance ◽  
Impeller Geometry

The main focus of this work is on the geometrical modifications that can be applied to the fan wheel and the volute tongue of a radial fan to reduce the tonal noise. The experimental measurements are performed by using the in-duct method in accordance with ISO 5136. In addition to the experimental measurements, CFD (Computational Fluid Dynamics) and CAA (Computational Aeroacoustics) simulations are carried out to investigate the effects of different modifications on the noise and performance of the fan. It is shown that by modifying the blade outlet angle, the tonal noise of the fan can be reduced without affecting the performance of the fan. Moreover, it is indicated that increasing the number of blades leads to a significant reduction in the tonal noise and also an improvement in the performance. However, this trend is only valid up to a certain number of blades, and a further increment might reduce the aerodynamic performance of the fan. Besides modifying the impeller geometry, new volute tongues are designed and manufactured. It is demonstrated that the shape of the volute tongue plays an important role in the tonal noise generation of the fan. It is possible to reduce the tonal noise by using stepped tongues which produce phase-shift effects that lead to an effective local cancellation of the noise.

Computational Fluid Dynamics Modeling of Mixed Convection Flows in Building Enclosures

2013 ◽  
Author(s):  
Alexander Kayne ◽  
Ramesh Agarwal
Keyword(s):  
Heat Transfer ◽  
Fluid Dynamics ◽  
Experimental Data ◽  
Computational Fluid Dynamics ◽  
Mixed Convection ◽  
Turbulence Model ◽  
Numerical Algorithm ◽  
Navier Stokes ◽  
Cfd Simulations ◽  
Flow And Heat Transfer

In recent years Computational Fluid Dynamics (CFD) simulations are increasingly used to model the air circulation and temperature environment inside the rooms of residential and office buildings to gain insight into the relative energy consumptions of various HVAC systems for cooling/heating for climate control and thermal comfort. This requires accurate simulation of turbulent flow and heat transfer for various types of ventilation systems using the Reynolds-Averaged Navier-Stokes (RANS) equations of fluid dynamics. Large Eddy Simulation (LES) or Direct Numerical Simulation (DNS) of Navier-Stokes equations is computationally intensive and expensive for simulations of this kind. As a result, vast majority of CFD simulations employ RANS equations in conjunction with a turbulence model. In order to assess the modeling requirements (mesh, numerical algorithm, turbulence model etc.) for accurate simulations, it is critical to validate the calculations against the experimental data. For this purpose, we use three well known benchmark validation cases, one for natural convection in 2D closed vertical cavity, second for forced convection in a 2D rectangular cavity and the third for mixed convection in a 2D square cavity. The simulations are performed on a number of meshes of different density using a number of turbulence models. It is found that k-epsilon two-equation turbulence model with a second-order algorithm on a reasonable mesh gives the best results. This information is then used to determine the modeling requirements (mesh, numerical algorithm, turbulence model etc.) for flows in 3D enclosures with different ventilation systems. In particular two cases are considered for which the experimental data is available. These cases are (1) air flow and heat transfer in a naturally ventilated room and (2) airflow and temperature distribution in an atrium. Good agreement with the experimental data and computations of other investigators is obtained.

Three Dimensional Simulation of the Effect of Windcatcher’s Inlet Shape

2019 ◽  
Author(s):  
Peter Abdo ◽  
Rahil Taghipour ◽  
B. P. Huynh
Keyword(s):  
Fluid Dynamics ◽  
Computational Fluid Dynamics ◽  
Indoor Environment ◽  
Natural Ventilation ◽  
Air Flow ◽  
Three Dimensional ◽  
Sectional Area ◽  
Cross Sectional ◽  
Dimensional Simulation ◽  
Convergent Inlet

Abstract Windcatcher has been used over centuries for providing natural ventilation using wind power, it is an effective passive method to provide healthy and comfortable indoor environment. The windcatcher’s function is based on the wind and on the stack effect resulting from temperature differences. Generally, it is difficult for wind to change its direction, and enter a room through usual openings, the windcatcher is designed to overcome such problems since they have vertical columns to help channel wind down to the inside of a building. The efficiency of a windcatcher is maximized by applying special forms of opening and exit. The openings depend on the windcatcher’s location and on its cross sectional area and shape such as square, rectangular, hexagonal or circular. In this study the effect of the inlet design is investigated to achieve better air flow and increase the efficiency of windcatchers. To achieve this, CFD (computational fluid dynamics) tool is used to simulate the air flow in a three dimensional room fitted with a windcatcher based on the different inlet designs. The divergent inlet has captured the highest air flow with a difference of approximately 3% compared to the uniform inlet and 5% difference compared to the bulging-convergent inlet.

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