1 Introduction

Numerous tall buildings are already being constructed or developing all around the world. Peoples are migrating to urban areas now-a-days. In order to accommodate such big population in cities, many lands are occupied by the building authorities for the construction of high-rise building projects. Construction of these high-rise structures becomes difficult when available land have many irregularities in terms of size and shape. Therefore, the construction of tall buildings having irregular cross-sectional shapes is the better idea to overcome these irregular land problems. Wind effects on such irregular shape high-rise structures are the major concern for the structural designer due to unavailability of wind data. Instead of designing the irregular shape building, the design of regular shape tall buildings is possible through different international standards [1,2,3,4,5,6,7]. The available international standards are discussing the wind effects on regular shape structure and silent in case of irregular shape structure. The wind induced effects can be obtained on such irregular structures by two major available options like one is wind tunnel testing [8, 9] and other is computational fluid dynamics methods [10,11,12]. In this research evaluation of wind effects is done using numerical simulation technique i.e. ANSYS CFX.

Wind effects on high-rise structures have been investigated by many researchers using wind tunnel test like Nagar et al [13] executed an experimental study on “H” shaped high rise buildings. Kwok [14] investigated the wind induced response on the various shape of tall buildings. Blessmann and Riera [15] performed the test in wind tunnel and obtained the wind induced response on the interfering tall buildings. Pal et al [16] performed the experiment in boundary layer wind tunnel on square plane shape model and remodel triangle shape model of high rise structure. Sharma et al [17] presented the techniques of reducing wind load by modifying the corner configuration on tall buildings. Yi and Li [18] studied the wind effects on a super tall building using wind tunnel techniques and compared the result on full scale building. Bairagi and Dalui [19] compared the aerodynamic coefficients of setback tall building for wind load. Bhattacharyya and Dalui [20] performed experiment and simulation on “E” shape tall building to investigate the mean wind pressure. Bearman and Morel [21] studied the effect of free stream turbulence effect of flow around bluff bodies. Raj and Ahuja [22] performed the experiment on a cross shape tall building. Raj et al [23] studied the response of square and plus shape building by varying wind load. Li et al [24] investigated the wind induced torque on “L” shape tall building. Blackmore [25] explored the design of building structures using wind tunnel method and concluded from experimental research that the design data available in various standards are in adequate. During design of tall building, the evaluation of wind load is necessary for such structures whose design data are absent, building having both the side setback is affected more with respect to single side setback. Limited research work done for interference of the building such as Hui et al [26] done the experiment in wind tunnel for two rectangular building model. Pal and Raj [27] evaluated the wind induced interference effect on remodeled shape tall building. Zu and Lam [28] investigated the across wind response of interference for twin tall buildings. Nagar et al [29] on two plus plan shape tall building. Gaur et al [30] investigated the interference effect on corner configured structure using CFD. Important outcomes from these findings such as pressure distribution for isolated building and as well as in full blockage condition. The interference effect is more on the principal building if the interfering building is located on the upstream of wind. Corner cut model configuration helps to reduce the drag force and flow separation at the principal model.

Investigation of wind effects on irregular shape can be possible by using various available tools such as experimental and numerical methods. However, experimental methods are time consuming and having some types of limitations. Computational fluid dynamics techniques are employed to evaluate the wind effect on such irregular shape high rise structure in order to overcome such limitations. Rajasekarababu and Vinayagamurthy [31] investigated wind effects on setback building. Taniguchi and Akamine [32] analyzed the wind pressure coefficient on detached houses in a dense residential block. Zheng et al [33] predicted the improvement of inflow boundary conditions in the numerical simulation to investigate the wind flow around the tall building. Haque et al [34] estimated the flow fields around rectangular cylinder under turbulent flow by large eddy simulation turbulence model. Gaur and Raj [35] numerically investigated the wind loads effects on a square shape building model. Mou et al [36] performed a numerical simulation to observe the variation in pressure distribution on various building models. Hu et al [37] numerically observed the mean wind speed and turbulence intensity effect on tall building using shear stress transport and k-ω turbulence model. Blocken et al [38] provided recommendation for accurate CFD simulation for atmospheric boundary layer flow. Bairagi and Dalui [39] evaluated wind generated effect on stepped tall building. Wind induced effect are investigated by various researcher like Kumar and Raj [40] on octagonal plan oval shape building, Okajima [41] on rectangular cylinder, Mallick et al [42] on “C” shape, Stathopoulos and Baskaran [43] discussed wind environmental conditions around tall buildings, Cheng et al [44] evaluated the wind pressure effect and aerodynamics forces on tall building of square shape, Bhattacharjee et al [45] on butterfly plan shape tall buildings, Tang et al [46] numerically simulated on polygonal buildings, Zheng and Zhang [47] investigated the drag effects on the controlled suction on high rise building, Bairagi and Dalui [48] on setback building, Raj [49] analyzed the response of plus shaped tall building with different bracing system under wind load, the notable outcomes from these numerical studies are as mean pressure on wind ward face will have positive values while other faces will be under the impact of negative pressure. The height and distance of neighboring buildings contribute significantly to external wind flow patterns. Wake length is the governing factor that controls the drag force on high-rise structures. Numerical computations time can be reduced by employing shear stress transport and k-ω turbulence model and Reynold's number is strongly dependent on the breadth to width ratio of the building model. Pressure distribution patterns are mainly influenced by wind flow at different angle and available terrain surrounding the tall structures. Wind fluctuation increases with the increment in the opening in the high-rise structure and generated drag force decreases by twisting the building model shape. The influence of wind can be reduced on high-rise building by controlling the suction. Building with double side setback is efficient to maintain the velocity at the pedestrian level.

In this research study, two corners modified rectangular regular building model and two corners modified Y-shape irregular building models are considered having equal cross-sectional area and height. Corners having the modification such as corner cut, chamfer and fillet etc. helps to reduce the wind impact on high rise structure because of that in this research a comparative study on chamfer and fillet corners are selected. The numerical analysis on such shapes of high-rise building is performed using ANSYS CFX. A very few amount research is done on such type of comparison and this comparison will help a structural designer to choose the building shape having equal cross-sectional area.

2 Methodology

The numerical investigation is performed on the regular and irregular shape building model using ANSYS CFX, before the starting of the work validation study was carried out and the results are found similar to the experimental results and various international standards.

2.1 Numerical simulation

Numerical simulation is performed as per the guidelines available in ANSYS CFX Solver modeling guide [50]. Some basic equations are utilized in numerical simulation, such as the Navier Stock equation and continuity equation.Navier Stokes equation

$$\frac{\partial \left(\rho {u}_{i}\right)}{\partial t}=-\frac{\partial \left(\rho {u}_{i}{u}_{j}\right)}{\partial {x}_{j}}-\frac{\partial P}{\partial {x}_{j}}+\frac{\partial }{{\partial }_{{x}_{j}}}\left[\mu \left(\frac{{\partial }_{{u}_{i}}}{{\partial }_{{x}_{j}}}+\frac{{\partial }_{{u}_{j}}}{{\partial }_{{x}_{i}}}\right)\right]+F$$
(1)
$$ {\text{Acceleration term}} = - {\text{Convection term}} - {\text{Pressure gradient}} + {\text{Effects of viscosity}} + {\text{Body force}} $$

Continuity equation

$$\frac{{\partial }_{\rho }}{{\partial }_{t}}+\frac{{\partial }_{{\rho }_{i}}}{{\partial }_{{x}_{i}}}=0$$
(2)

Eddy viscosity

$$ \mu_{t = } \rho c_{\mu } \frac{{k^{2} }}{ \in } $$
(3)

where \({c}_{\mu }\) is the dimensionless constant;

This research study is performed by utilizing the k-ε turbulence model, which is two-equation model.

The standard k-ɛ model uses the following transport equations for the turbulence kinetic energy and turbulence dissipation rate:

$$ \frac{\partial (\rho k)}{{\partial t}} + \frac{\partial }{{\partial x_{j} }}(\rho U_{j} k) = \frac{\partial }{{\partial x_{j} }}\left[ {\left( {\mu + \frac{{\mu_{t} }}{{\sigma_{k} }}} \right)\frac{\partial k}{{\partial x_{j} }}} \right] + P_{k} - \rho \varepsilon + P_{kb} $$
(4)
$$ \frac{\partial (\rho \varepsilon )}{{\partial t}} + \frac{\partial }{{\partial x_{j} }}(\rho U_{j} \varepsilon ) = \frac{\partial }{{\partial x_{j} }}\left[ {\left( {\mu + \frac{{\mu_{t} }}{{\sigma_{k} }}} \right)\frac{\partial \varepsilon }{{\partial x_{j} }}} \right] + \frac{\varepsilon }{k}(C_{\varepsilon 1} P_{k} - C_{\varepsilon 2\rho \varepsilon } + C_{\varepsilon 1} P_{\varepsilon b} ) $$
(5)

where \({C}_{\varepsilon 1},{C}_{\varepsilon 2}, {\sigma }_{k}\, and\, {\sigma }_{\varepsilon }\) are constant; \({P}_{kb}\) and \({P}_{\varepsilon b}\) Represent the influence of the buoyancy forces; \({P}_{k}\) Turbulence production due to viscous forces, which is modeled using.

$${P}_{k}=\mu \left(\frac{\partial {U}_{i}}{\partial {x}_{j}}+\frac{\partial {U}_{j}}{\partial {x}_{i}}\right)\frac{\partial {U}_{i}}{\partial {x}_{j}}-\frac{2}{3}\frac{\partial {U}_{k}}{\partial {x}_{k}}\left(3{\mu }_{t}\frac{\partial {U}_{k}}{\partial {x}_{k}}+\rho k\right)$$
(6)

2.2 Model

The irregular shape building models are depicted in figure 1 with dimensions and wind incidence angles. The aim of this study is to investigate the wind effects on equal area model by keeping the same ratio of modifications. For these purpose the dimension of such corners and the height of buildings model are same. Models are prepared in ANSYS, CFX design modular by designing the geometry and then extrude of 750 mm height is applied for each case of the tall building model.

Figure 1
figure 1

Building model in plan and isometric view.

Full size image

2.3 Meshing

Meshing plays a very important role in numerical simulation and done as per the available guidelines in ANSYS Meshing User’s Guide [51], meshing is of two types, structured that follows a fix pattern of mesh and this is generally hex or quad meshing. Unstructured mesh that does not follow the uniform pattern and sometimes it may produce the irrelevance results. Poor meshing will give error in numerical simulation or will require more computational resources also there may be a chance of bad solution thus for this study the meshing adopted in this numerical simulation is demonstrated in figure 2. The meshing on building is finer than the ground meshing and domain meshing while inflation is also provided to capture the flow behaviour more accurately. Very fine meshing will need more time and high-end computational resources to perform the simulation and it’s not mandatory that very fine meshing will generate the accurate solution while this may produce the irrelevant results.

Figure 2
figure 2

Description of meshing.

Full size image

2.4 Domain

The domain is the environment where the numerical simulation is performed. Various recommendations are available for constructing the domain such as Zidan et al [52] optimize the fluid domain in CFD simulation for tall buildings, domain used in this study is presented with dimensions in figure 3, this domain is constructed on the recommendation provided by Revuz et al [53] also the most of the studies in the past is already produces the numerical simulation results on the basis of domain presented in figure 3.

Figure 3
figure 3

Domain.

Full size image

The sidewall and inlet of the domain are kept at 5H. The outlet is at 15H and height of the domain is at 6H, where H is the height of the building model, such large domain is constructed in the design modular for proper wake generation behind the building model. The sidewall and top are assigned as free slip. Ground of the domain where building model is placed and the wall of the building models are assigned as no-slip wall, free slip wall means that velocity is same as that of the inlet and no-slip means that the velocity distributed as per the power low defined at the inlet.

2.5 Turbulent intensity and mean wind speed profile

Wind incident on tall buildings is followed by power-law index of wind distribution available for all types of terrain. Generally, wind speed is increases with respect to height and wind speed on the ground is almost zero due the obstruction faces at ground level. Wind velocity become gradient height becomes constant and this is known as free stream wind or gradient wind. Mean wind speed and turbulent intensity are presented in figure 4, the boundary conditions are kept similar with those experimental performed by Raj [54] in boundary layer wind tunnel and comparative graph is also presented to validate the numerical study with the experimental study.

Figure 4
figure 4

Mean wind speed and turbulent intensity profile numerical simulation and experimental.

Full size image

Mean wind speed and turbulent intensity profile should be defined at the inlet to performed the numerical simulation. The boundary layer mean wind speed profile is governed by the power-law equation (eq.7) and the same is applied in the numerical simulation.

$$U={U}_{h}{\left(\frac{Z}{{Z}_{H}}\right)}^{\alpha }$$
(7)

where \({U}_{h}\) is the boundary layer velocity, which is 10 m/s for this study; \(Z\) is the reference height; \(U\) is the mean wind speed at a reference height \(Z\); α is a parameter that varies with ground roughness. (Known as power law index); \({Z}_{H}\) is the boundary layer depth;

$${I}_{z}=\frac{{\sigma }_{z}}{U\left(z\right)}$$
(8)

where \({I}_{z}\) is the turbulence intensity at height z; \({\sigma }_{z}\) is the standard deviation of the wind speed at height z; \(U\left(z\right)\) is the mean wind speed at height z.

2.6 Validation

The solution obtained with the help of numerical techniques are validated with three standards models represented in figure 5. Numerical findings are depicted in the graphical form in figure 6 and table 1. Results presented in paper are identical with experimental and different international standards.

Figure 5
figure 5

Validation model with dinemsions.

Full size image
Figure 6
figure 6

Results validation with experimental and different international standards.

Full size image
Table 1 Comparison of face average pressure coefficient (Cp) on the model-3 of tall building.
Full size table

The results of mean Cp are calculated and compared with experimental study performed by Amin and Ahuja [55], Raj [54], Raj et al [23] as well as with the numerical finding of Sanyal and Dalui [56], Kumar and Dalui [57] and the result on model-1 is compared with different international standards [1,2,3, 5, 6, 58].

The external pressure coefficient “ \({C}_{p}\)” is calculated using the equation (9).

$${C}_{p}=\frac{p-{p}_{o}}{\frac{1}{2}\rho {{U}_{H}}^{2}}$$
(9)

2.7 Grid convergence

In this study a grid convergence study was performed on model-1. Grid convergence study is necessary for a CFD programming as it helps to know the accuracy of CFD solver settings. For the present study GC-3 is adopted for all the wind incidence angle varies from 0° to 180° at the interval of 15° each. In this study the grid convergence study is performed on the basis of procedure provided by Celik et al [59], Derakhshandeh and Alam [60]. The percentage error is reported in the table 2 and GC-3 is adopted because of the less percentage error reported in the mean Cp compared with the IS: 875 (part-3): 2015 [5] for 0° wind incidence angle. The grid convergence study is performed on five different cases by varying the meshing type namely coarse, medium and fine. Number of elements for coarse, medium and fine meshing are 957324, 1439589 and 2497236 respectively. Grid convergence study is performed on model-1 while for validation purposes the three model are taken into consideration and validation study is performed on model-1, 2 and 3.

Table 2 Grid convergence test result for model-1.
Full size table

3 Result and discussion

Results of pressure distribution and velocity streamlines are discussed and presented in a graphical and external Cp is tabulated for the building model- A, model- B, model- C and model- D.

3.1 Horizontal pressure distribution at mid height of building models

The pressure distribution along the peripheral distance for various building models are presented in figure 7. The pressure distribution along peripheral length are presented at mid height of building in form of graph at 0° to 180° at an interval of 15°. The pressure distribution for building model-A and model-B is of same nature for 90° winds. Figure 8 presented the pressure distribution for model-A, model-B, model-C and model-D. Face-A under the direct exposure to wind depicted positive pressure distribution throughout the face and it is seen that the maximum positive pressure for model-A is 1.05 on face-A at 0° and 15° wind incidences while for face-B at 45° and face-C at 60° & 75° wind incidence angles. The minimum pressure of −1.64 is noted at 832 mm on face-H at 30° wind, which is 156 % less from the maximum positive pressure.

Figure 7
figure 7

Peripheral distance along the building model-A, model-B, model-C and model-D.

Full size image
Figure 8
figure 8figure 8figure 8

Pressure distribution along with the peripheral distance for model-A, model-B, model-C and model-D.

Full size image

The maximum positive pressure for model-B, is 1.07 at 220 mm which is generated at face-C in case of 90° wind incidence angle and the minimum negative pressure is −1.94 noted on face-A in the case of 90° wind incidence angle at 56 mm of peripheral distance, maximum negative pressure observed on model-B that is almost 180 % of maximum positive pressure. It can be concluded from the results that model-A is more efficient in terms of pressure distribution with respect to model-B having fillet corners. Y- shape building model with chamfer corners i.e. model-C having the maximum pressure of 0.79 at 15 mm and 450 mm peripheral distance on face-A in case of 90° & 120° wind incidence angle respectively.

The minimum pressure of −1.76 which is more than maximum positive pressure on model-C, and similar observation found at 912 mm peripheral distance in case of model-D at 0° wind angle. Y- shape with round corner in each limb having the maximum and minimum pressure of 0.85 at 15 mm and −2.01 detect at 905 mm on face-A at 0° wind angle respectively. Among the model-C and model-D the maximum efficient model is model-C which is having the chamfer shape in each limb of irregular Y- shape.

3.2 Velocity streamlines

The Velocity streamlines are presented pictorially for model-A (Rectangular Chamfer) in figure 9 from 0° to 90° wind incidence angle at 15° intervals. Streamlines are obtained from ANSYS CFX Post processing. The wind flow pattern is clearly presenting the size of wake in downstream of the wind, maximum wake is observed for 90° winds as the model is obstructing more wind flow with respect to 0° wind angle and thus the wake is increasing. The pattern of vortex formed in the downstream is changing at each wind angle also, the reattachment of the flow is more in the case of 0° wind.

Figure 9
figure 9

Velocity Streamlines for model-A at 0° to 90° wind incidence angles at an interval of 15°

Full size image

3.3 Numerical simulation ISO surface of pressure

The ISO-surface of pressure is a three-dimensional visualization which present the physical shape of pressure distribution around the building model and is obtained through ANSYS CFX Post by applying Q-Criterion [61, 62]. The ISO-surface of pressure is generated and presented in figure 10 for building model- A, model- B, model- C and model- D.

Figure 10
figure 10

ISO Surface of Pressure around building model-A, model-B, model-C and model-D.

Full size image

3.4 External pressure coefficient

The external pressure coefficient on the high-rise structure helps designer to calculate the wind effects on such tall buildings. External pressure coefficient for building model-A i.e., rectangular chamfer shown in figure 11 and numerical output are presented in table 3. After the observation face-B and face-H have slightly similar pressure coefficients. The highest pressure observed at 0° wind angle and it is found (0.91) on the face-A, smallest pressure (−1.11) is spot on face-A in case of 75° wind incidence angle. The external pressure coefficient is more or less equivalent with each other in the case of wind ward faces (the face which is in the directly exposure to wind). It is discovered that identical face having uniform pressure coefficient for particular wind incidence angle.

Figure 11
figure 11

Building models (A) Rectangular Chamfer and (B) Rectangular Fillet.

Full size image
Table 3 External pressure coefficient for building model-A (Rectangular chamfer).
Full size table

The External pressure coefficient evaluated for building model-B presented in figure 11 (Rectangular fillet) is tabulated in table 4, at 0° to 90° wind incidence angles at the interval of 15°. Maximum positive pressure (0.71) is detected on face-A at 0° wind incidence angle while the least pressure (-1.49) is noticed on face- B and face- D in the case of 90° wind incidence angle.

Table 4 External pressure coefficient for building model-B (Rectangular fillet).
Full size table

The external pressure coefficient calculated and tabulated in table 5 for building model-C (Y-shape Chamfer) presented in figure 12. Research study is done on Y- shape for 0° to 180° wind incidence angle while for rectangular model 0° to 90° wind incidence angle. The external pressure coefficient is presented in a tabular form in table 3, the highest pressure (0.69) is observed at face-C in the case of 45° wind incidence and minimum pressure (−1.14) is noticed on face-E, at 150° wind. This is concluded that symmetric face is having identical nature of pressure distribution are observed for 0°, 60°, 120° and 180° wind. for building model-D (Y-shape Fillet) represented in figure 12, the external pressure coefficients are tabulated in table 6, the maximum pressure (0.69) is noticed on the face-A, face-C, face-D, face-F and face-H at 0°, 45°, 75°, 120° and 165° respectively and minimum pressure (−1.4) on face-L in the case of 15° wind incidence angle. The maximum positive pressure for building models- B and C is nearly of same magnitude on the wind ward face while in the case of negative pressure it is 22 % more for model- D with respect to model- C.

Table 5 External pressure coefficient for building model-C (Y-shape Chamfer).
Full size table
Figure 12
figure 12

Building models (C) Y-shape Chamfer and (D) Y-shape Fillet.

Full size image
Table 6 External pressure coefficient for building model-D (Y-shape fillet).
Full size table

3.5 Base shear

Base shear is derived from the results obtained through the computational fluid dynamic tool ANSYS CFX. The force is calculated on the base and presented in graphical form in figure 13 for the building models considered in this study. The largest base shear along x-direction that is a drag for model- A is 1.84 for at 45° and 135° while for model- B the maximum drag is 1.68 at 30° and 135° in the case of the model- C the drag of 0.65 is maximum at 60° and 180°. The drag of 0.66 is found maximum for model-D at 60° and 180° wind incidence angles. Lift force is calculated and presented in figure 13 the minimum lift force is found −1.05 for model-A at 45° and 135° while on model-B the least lift force is −0.98 at 45° and 135° wind incidence angles.

Figure 13
figure 13

Drag and Lift Force coefficient for model-A, model-B, model-C and model-D at 0° to 180° wind incidence angle.

Full size image

Y-shape model-C having chamfer edges at the end of each limb is having the highest and lowest lift as 0.58 at 90° and −0.25 at 165° respectively, while the model- D having round in corner in each limb of Y-shape having the maximum lift of 0.46 and it is spotted at 90° and minimum of −0.45 in noted at 30° winds. Base shear in x and y direction are \({C}_{{f}_{x}}\) & \({C}_{{f}_{y}}\) and it is calculated using equation 10 and equation 11 where \({F}_{x}\) & \({F}_{y}\) is the base force obtained through numerical simulation, \({U}_{h}\) is the reference wind speed at height h and \({A}_{p}\) is the projected area.

$${C}_{{f}_{x}}=\frac{{F}_{x}}{\left(0.5{\rho }_{{{U}_{h}}^{2}}.{A}_{p}\right)}$$
(10)
$${C}_{{f}_{y}}=\frac{{F}_{y}}{\left(0.5{\rho }_{{{U}_{h}}^{2}}.{A}_{p}\right)}$$
(11)

3.6 Base moment

The base moment for model-A, B, C & D are presented in figure 14, moments are calculated at the base of the building model. The maximum Mx is 1.63 for model-A at 30° and 150° wind while for model-B is 1.06 at 45° and 135° wind incidence angle. The greatest CMx for model- C is 0.30 at 90° and 150° wind while for model-D the maximum is 0.25 at 150° wind incidence angle. The base moment in the y-direction is found extreme of 1.95 for model-A at 45° and 135° wind angle while for model-C the maximum CMy is 0.36 at 90° and for model having round corner in each limb of Y-shape is having the maximum CMy of 0.34 at the 90°- wind incidence angle. Base moment along x and y direction are \({C}_{{M}_{x}}\) & \({C}_{{M}_{y}}\) where \({M}_{x}\) and \({M}_{y}\) is the base moment obtained through the numerical simulation, \({U}_{h}\) is the reference wind speed at height h, \({A}_{p}\) is the projected area and H is the height of the building model.

Figure 14
figure 14

Base moment along X (CMx) and Y (CMy) for model-A, model-B, model-C and model-D at 0° to 180° at an interval of 15° wind incidence angle.

Full size image
$${C}_{{M}_{x}}=\frac{{M}_{x}}{\left(0.5{\rho }_{{{U}_{h}}^{2}}.{A}_{p}.H\right)}$$
(12)
$${C}_{{M}_{y}}=\frac{{M}_{y}}{\left(0.5{\rho }_{{{U}_{h}}^{2}}.{A}_{p}.H\right)}$$
(13)

4 Conclusion

This research study is performed using ANSYS CFX on various shape building models and presents the comparison between regular and irregular shape building models having different corner configurations. The results obtained through numerical techniques is validated with the experimental results and different international standards. The significant outcomes from the present study are noted as follows.

  • The validation study shows the very prominent results for model-1, model-2 and model-3, also the results obtained for CPmean are found significantly in the closer range with experimental as well as with different international standards.

  • Pressure distribution along the peripheral distance for building model having equal cross-sectional area are discussed and presented in the graphical form for model-A, model-B, model-C and model-D at the interval of 15° for the wind incidence angle varies between 0° to 180°.

  • While comparing the models- C & D, maximum pressure along the peripheral distance found in model-D and in the case of model-A & B, the maximum positive pressure is observed for model-B, out of all four models, the model- D is having lesser pressure than the model- B.

  • Out of all models, the model having round in corner Y-shape has the minimum overall base moment which is 24 % less than the model-A rectangular chamfer. Model-A & B which is having equal number of faces, the lowest external pressure coefficient is observed for model-B in the case of 15° wind incidence angle. On comparing model-C & D, model-D is more aerodynamic with respect to model-C.

  • The present study is comparing the result of equal cross sectional area buildings. The dimensions of the modifications are kept same for all model and it is found that the minimum drag force is obtained for model-D which is having round corner in each limb of Y-shape.