Numerical Study of the Laminar Flow Past a Rotating Square Cylinder at Low Spinning Rates

2014 ◽  
Vol 137 (2) ◽  
Author(s):  
Dipankar Chatterjee ◽  
Satish Kumar Gupta
Keyword(s):  
Rotational Speed ◽  
Stream Flow ◽  
Free Stream ◽  
Stokes Equations ◽  
Numerical Study ◽  
Fluid Dynamic ◽  
Low Frequency ◽  
Square Cylinder ◽  
Rotating Circular Cylinder ◽  
Critical Rotational Speed

The fluid dynamic interaction between a uniform free stream flow and the rotation induced flow from a sharp edged body is numerically investigated. A two-dimensional (2D) finite volume based computation is performed in this regard to simulate the laminar fluid flow around a rotating square cylinder in an unconfined medium. Body fitted grid system along with moving boundaries is used to obtain the numerical solution of the incompressible Navier–Stokes equations. The Reynolds number based on the free stream flow is kept in the range 10≤Re≤200 with a dimensionless rotational speed of the cylinder in the range 0≤Ω≤5. At low Re=10, the flow field remains steady irrespective of the rotational speed. For 50≤Re≤200, regular low frequency Kármán vortex shedding (VS) is observed up to a critical rate of rotation (Ωcr). Beyond Ωcr, the global flow shows steady nature, although high frequency oscillations in the aerodynamic coefficients are present. The rotating circular cylinder also shows likewise degeneration of Kármán VS at some critical rotational speed. However, significant differences can be seen at higher rotation. Such fluid dynamic transport around a spinning square in an unconfined free stream flow is reported for the first time.

A numerical study of the interaction between unsteay free-stream disturbances and localized variations in surface geometry

1989 ◽  
Vol 209 ◽  
pp. 285-308 ◽  
Author(s):  
R. J. Bodonyi ◽  
W. J. C. Welch ◽  
P. W. Duck ◽  
M. Tadjfar
Keyword(s):  
Numerical Solutions ◽  
Free Stream ◽  
Stokes Equations ◽  
Numerical Study ◽  
Navier Stokes ◽  
Surface Geometry ◽  
Navier Stokes Equations ◽  
S Waves ◽  
Tollmien Schlichting

A numerical study of the generation of Tollmien-Schlichting (T–S) waves due to the interaction between a small free-stream disturbance and a small localized variation of the surface geometry has been carried out using both finite–difference and spectral methods. The nonlinear steady flow is of the viscous–inviscid interactive type while the unsteady disturbed flow is assumed to be governed by the Navier–Stokes equations linearized about this flow. Numerical solutions illustrate the growth or decay of the T–S waves generated by the interaction between the free-stream disturbance and the surface distortion, depending on the value of the scaled Strouhal number. An important result of this receptivity problem is the numerical determination of the amplitude of the T–S waves.

Experimental and Numerical Study of Vortex Induced Vibrations on a Spool Model

2018 ◽  
Author(s):  
David Gross ◽  
Yann Roux ◽  
Benjamin Rousse ◽  
François Pétrié ◽  
Ludovic Assier ◽  
...  
Keyword(s):  
Stokes Equations ◽  
Numerical Study ◽  
Fluid Dynamic ◽  
Navier Stokes ◽  
Navier Stokes Equations ◽  
Flow Perturbation ◽  
Industry Standards ◽  
Vortex Induced Vibrations ◽  
Recommended Practices ◽  
Decay Tests

The problem of Vortex-Induced Vibrations (VIV) on spool and jumper geometries is known to present several drawbacks when approached with conventional engineering tools used in the study of VIV on risers. Current recommended practices can lead to over-conservatism that the industry needs to quantify and minimize within notably cost reduction objectives. Within this purpose, the paper will present a brief critical review of the Industry standards and more particularly focus on both experimental and Computational Fluid Dynamic (CFD) approaches. Both qualitative and quantitative comparisons between basin tests and CFD results for a 2D ‘M-shape’ spool model will be detailed. The results presented here are part of a larger experimental and numerical campaign which considered a number of current velocities, heading and geometry configurations. The vibratory response of the model will be investigated for one of the current velocities and compared with the results obtained through recommended practices (e.g. Shear7 and DNV guidelines). The strategy used by the software K-FSI to solve the fluid-structure interaction (FSI) problem is a partitioned coupling solver between fluid solver (FINE™/Marine) and structural solvers (ARA). FINE™/Marine solves the Reynolds-Averaged Navier-Stokes Equations in a conservative way via the finite volume method and can work on structured or unstructured meshes with arbitrary polyhedrons, while ARA is a nonlinear finite element solver with a large displacement formulation. The experiments were conducted in the BGO FIRST facility located in La Seyne sur Mer, France. Particular attention was paid towards the model design, fabrication, instrumentation and characterization, to ensure an excellent agreement between the structural numerical model and the actual physical model. This included the use of a material with low structural damping, the performance of stiffness and decay tests in air and in still water, plus the rationalization of the instrumentation to be able to capture the response with the minimum flow perturbation or interaction due to instrumentation.

Numerical Prediction of Turbulent Wakes Behind a Square Cylinder

1998 ◽  
Vol 14 (1) ◽  
pp. 23-29
Author(s):  
Robert R. Hwang ◽  
Sheng-Yuh Jaw
Keyword(s):  
Stokes Equations ◽  
Numerical Study ◽  
Navier Stokes ◽  
Wall Region ◽  
Square Cylinder ◽  
Mean Velocity ◽  
Navier Stokes Equations ◽  
Turbulent Vortex Shedding ◽  
Model Equations ◽  
Good Agreement

ABSTRACTThis paper presents a numerical study on turbulent vortex shedding flows past a square cylinder. The 2D unsteady periodic shedding motion was resolved in the calculation and the superimposed turbulent fluctuations were simulated with a second-order Reynolds-stress closure model. The calculations were carried out by solving numerically the fully elliptic ensemble-averaged Navier-Stokes equations coupled with the turbulence model equations together with the two-layer approach in the treatment of the near-wall region. The performance of the computations was evaluated by comparing the numerical results with data from available experiments. Results indicate that the present study gives good agreement in the shedding frequency and mean drag as well as in some phase profiles of the mean velocity.

Numerical Study of Coal Composition Effects on the Performance of Gasification Through Computational Fluid Dynamic

2019 ◽  
Vol 17 (7) ◽  
Author(s):  
Imran Nazir Unar ◽  
Suhail Ahmed Soomro ◽  
Ghulamullah Maitlo ◽  
Shaheen Aziz ◽  
Rasool Bux Mahar ◽  
...  
Keyword(s):  
Computational Fluid Dynamic ◽  
Stokes Equations ◽  
Numerical Study ◽  
Fluid Dynamic ◽  
Great Influence ◽  
Electricity Production ◽  
Combustion Model ◽  
Heating Value ◽  
Coal Composition ◽  
Coal Reserves

Abstract Pakistan is very rich in coal reserves specifically after exploration of Thar coal reserves. At the same time country is facing energy crises due to shortage or unavailability of sustainable fuel supply at a cheaper rate. One potential solution is coal gasification which gives clean synthetic gas usually called syngas for use as an alternative fuel source for electricity production at a cheaper rate as well as a source of recovering different chemicals used as basic raw materials in other industries. Numerical simulations have been performed in this work for the gasification process of indigenous coal on a 2D computational fluid dynamic (CFD) model of downdraft entrained-flow gasifier using commercial CFD software FLUENT®6.3.26. Navier-stokes equations along with transport equations for species have been solved using eddy-dissipation combustion model. The compositions of indigenous coals (Thar, Lakhra, and Sonda) were used in simulations as gasification feedstock. Rich oxidant conditions 95 % O2 and 5 % N2 were set for gasification. The gasification performance was studied by comparing efficiencies of gasification and quality of syngas produced for three types of coal feedings. The temperature and pressure profiles inside the gasifier were also studied. From simulation results, the great influence of coal composition was observed in the performance of gasification. Lakhra coal produced syngas with a maximum heating value of 20.55 MJ/kg whereas sonda coal produced syngas with a minimum heating value of 17.96 MJ/kg.

Numerical study on the fluid flow pass a square cylinder: The temperature-viscosity dependence

2014 ◽  
Vol 25 (03) ◽  
pp. 1350101
Author(s):  
Jianhua Lu ◽  
Sheng Li ◽  
Zhaoli Guo ◽  
Baochang Shi
Keyword(s):  
Fluid Flow ◽  
Free Stream ◽  
Numerical Study ◽  
Effect Of Temperature ◽  
Square Cylinder ◽  
Efficient Tool ◽  
Multiple Relaxation Time ◽  
Upward Velocity ◽  
Drag And Lift ◽  
Viscosity Dependence

In this paper, the 2D fluid flow pass a heated/cooled square cylinder exposed to a constant free-stream upward velocity is simulated via a multiple relaxation time (MRT) lattice-Boltzmann (LB) method. The buoyancy effect on the drag and lift coefficients as well as Nusselt number related is compared with the results in the existing literatures to validate the code used. The effect of temperature-viscosity dependence is then investigated to test whether the effect can be neglected or not for the mixed convection case. It is shown that the effect cannot be ignored when |Ri| > 0.15. Fortunately, the effect can be captured by using an effective temperature formula [J. M. Shi, D. Ferlach, M. Breuer, G. Biswas and F. Durst, Phys. Fluids16, 4331 (2004)] in a rather large range of Ri. All the numerical results, from another angle, also demonstrate that the MRT method is an efficient tool in simulating the problems such as the present one.

Studies on Aerodynamic Characteristics of Dump Diffusers for Modern Aircraft Engines

2012 ◽  
Vol 232 ◽  
pp. 246-251 ◽  
Author(s):  
P. Sathyan ◽  
S. Srikanth ◽  
I. Dheepan ◽  
M. Arun ◽  
C. Aswin ◽  
...  
Keyword(s):  
Stokes Equations ◽  
Numerical Study ◽  
Fluid Dynamic ◽  
Aerodynamic Characteristics ◽  
Navier Stokes ◽  
Finite Volume Scheme ◽  
Aircraft Engines ◽  
Navier Stokes Equations ◽  
Dynamic Constraints ◽  
Fully Implicit

The geometrical optimization of dump diffusers are extremely demanding as the flow fields and stress fields are very complex and must be well understood to achieve the required design efficiencies. In this paper parametric analytical studies have been carried out for examining the aerodynamics characteristics of different dump diffusers for modern aircraft engines. Numerical studies have been carried out using SST K- ω turbulence model. This code solves SST k- ω turbulence equations using the coupled second order implicit unsteady formulation. In the numerical study, a fully implicit finite volume scheme of the compressible, Reynolds-Averaged, Navier-Stokes equations is employed. We concluded that in addition to the dump gap ratio, the aerodynamic shape of the flame tube case and the other geometric variables are also need to be optimized judiciously after considering the fluid dynamic constraints for controlling the pressure recovery and the losses.

Near-body vorticity dynamics of a square cylinder subjected to an inline pulsatile free stream flow

2016 ◽  
Vol 28 (9) ◽  
pp. 093605 ◽  
Author(s):  
Hrisheekesh Krishnan ◽  
Amit Agrawal ◽  
Atul Sharma ◽  
John Sheridan
Keyword(s):  
Stream Flow ◽  
Free Stream ◽  
Square Cylinder ◽  
Vorticity Dynamics

Numerical Simulation of Stirrer Oscillations in Consideration of Fluid-Structure-Interaction and Flexible Restraint Systems

2003 ◽  
Author(s):  
Thomas Berger ◽  
Klaus Strohmeier
Keyword(s):  
Rotational Speed ◽  
Fluid Dynamic ◽  
Dynamic Effects ◽  
Resonant Vibrations ◽  
Structural Dynamic ◽  
Structure Interaction ◽  
Critical Rotational Speed ◽  
Method Of Solution ◽  
Fully Coupled ◽  
Good Agreement

Stirrers are subjected to severe damages when the rotational speed n approaches the critical rotational speed nkrit (eigenfrequency). Appearing resonant vibrations result in huge stirrer shaft bending deformations and possible stirrer damages (see Figure 1). The possibilities of an accurate stirrer design (regarding the shaft vibrations) with analytical calculations [Fischer and Strohmeier (2000)] are often very unsatisfactional: The fluid dynamic effects on the structure and the real, often flexible, restraint systems cannot be considered. Both aspects, however, have an important influence, both on the critical rotational speed nkrit, and the oscillation amplitudes of the stirrer. As a method of solution, a fully coupled interaction of flow field and structural dynamic response of the stirrer is implemented in a commercial CFD-Code. The simulated results are compared to experimental data and show good agreement.

Numerical Study of Combined Radiation and Turbulent Mixed Convection Heat Transfer in a Compartment Containing Participating Media

2015 ◽  
Vol 31 (4) ◽  
pp. 467-480 ◽  
Author(s):  
A. Asghari ◽  
S. A. Gandjalikhan Nassab ◽  
A. B. Ansari
Keyword(s):  
Mixed Convection ◽  
Stokes Equations ◽  
Numerical Study ◽  
Fluid Dynamic ◽  
Convection Heat Transfer ◽  
Simple Algorithm ◽  
Convection Flow ◽  
Algebraic Equations ◽  
Mixed Convection Flow ◽  
Participating Media

AbstractThe effect of radiation on turbulent mixed convection flow, generated by two plane wall jets with different temperatures inside a cavity was studied numerically. The medium is treated as a gray, absorbing, emitting and scattering. The two-dimensional Reynolds-average Navier-Stokes equations, coupled with the energy equation are solved by using the computational fluid dynamic (CFD) techniques, while the AKN low-Reynolds-number model is employed for computation of turbulence fluctuations. The Boussinesq approximation is used to calculate the buoyancy term, and the radiation part of the problem is solved by numerical solution of the radiative transfer equation (RTE) with the well known discrete ordinate method (DOM). The governing equations are discretized by the finite volume technique into algebraic equations and solved with the SIMPLE algorithm. The effects of radiation conduction parameter, scattering albedo, optical thickness and Richardson number on the thermal behavior of the system are carried out. Results show that the gas radiation has a significant effect on the temperature distribution inside the turbulent mixed convection flow.

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