Skip to main content
SpringerLink
Log in

Control of flow in forced jets: a comparison of round and square cross sections

  • Regular Paper
  • Published:
Journal of Visualization Aims and scope Submit manuscript

Abstract

Direct numerical simulation of incompressible, spatially developing round and square jets at a Reynolds number of 1,000 is performed. The effect of two types of inlet perturbation on the flow structures is analyzed. First, dual-mode excitation, which is a combination of axisymmetric perturbation at preferred mode frequency and helical perturbation at sub-harmonic frequency is used, having a disturbance frequency ratio equal to R f  = 2. It is observed that the circular and square jets bifurcate and spread on one of the orthogonal planes forming a Y-shape jet in the downstream while no spreading is visible on the other plane. The second type of perturbation is a flapping excitation at a sub-harmonic frequency, St F = 0.2. It leads to a Y-shape bifurcation for both square and circular jets. On the other hand, for flapping excitation at the preferred mode frequency, namely, St F = 0.4, a circular jet bifurcates into a Ψ-shape whereas the square jet reveals simple spreading.

Graphical Abstract

This is a preview of subscription content, log in via an institution to check access.

Access this article

Log in via an institution

Price excludes VAT (USA)
Tax calculation will be finalised during checkout.

Instant access to the full article PDF.

Institutional subscriptions

Fig. 1
Fig. 2
Fig. 3
Fig. 4
Fig. 5
Fig. 6

Similar content being viewed by others

Abbreviations

D :

Nozzle diameter

Aa, Ah, Af:

Amplitude of axial, helical and flapping excitation, respectively

Re D :

Jet Reynolds number, \( {{U_{\text{inlet}} D} \mathord{\left/ {\vphantom {{U_{\text{inlet}} D} \nu }} \right. \kern-\nulldelimiterspace} \nu } \)

p :

Pressure

S ij :

Strain rate tensor, \( {{\left( {u_{i,j} + u_{j,i} } \right)} \mathord{\left/ {\vphantom {{\left( {u_{i,j} + u_{j,i} } \right)} 2}} \right. \kern-\nulldelimiterspace} 2} \)

St D , StH, StF:

Strouhal number for axial, helical and flapping perturbation respectively, \( St = {{fD} \mathord{\left/ {\vphantom {{fD} {U_{\text{inlet}} }}} \right. \kern-\nulldelimiterspace} {U_{\text{inlet}} }} \)

t :

Time

u noise i (r, t):

Noise (velocity) in i = x, y and z directions

u forced x (r, t):

Large-scale perturbation

u x , u y , u z :

Velocity in x, y and z directions

U inlet :

Maximum inlet velocity

x, y, z :

Cartesian coordinates

Ω ij :

Rotational tensor, \( {{\left( {u_{i,j} - u_{j,i} } \right)} \mathord{\left/ {\vphantom {{\left( {u_{i,j} - u_{j,i} } \right)} 2}} \right. \kern-\nulldelimiterspace} 2} \)

θ m :

Inlet momentum thickness, \( \int_{0}^{D/2} {{{\bar{u}} \mathord{\left/ {\vphantom {{\bar{u}} {U_{\text{inlet}} }}} \right. \kern-\nulldelimiterspace} {U_{\text{inlet}} }}} \left( {1 - {{\bar{u}} \mathord{\left/ {\vphantom {{\bar{u}} {U_{\text{inlet}} }}} \right. \kern-\nulldelimiterspace} {U_{\text{inlet}} }}} \right)r{\text{d}}r \)

θ c :

Azimuthal direction in cylindrical coordinate

ν :

Kinematic viscosity

References

  • da Silva CB, Metais O (2002) Vortex control of bifurcating jets: a numerical study. Phys Fluids 14:3798

    Article  MathSciNet  Google Scholar 

  • Danaila I, Boersma BJ (1998) Mode interaction in a forced homogeneous jet at low Reynolds numbers. In: Proceeding of the summer program. CTR, pp 141–158

  • Danaila I, Boersma BJ (2000) Direct numerical simulation of bifurcating jets. Phys Fluids 12:1255–1257

    Article  MATH  Google Scholar 

  • Ephrain G, Ho C-M (1983) Preferred modes and the spreading rates of jets. Phys Fluids 26:2932

    Article  Google Scholar 

  • Harlow FH, Welch JE (1966) Numerical study of large- amplitude free-surface motions. Phys Fluids 9:842

    Article  Google Scholar 

  • Hunt JCR, Wray AA, Moin P (1988) Eddies, stream, and convergence zones in turbulent flows. Report CTR-S88, Center for Turbulence Research

  • Lee M, Reynolds WC (1985) Bifurcating and blooming jets. Report TF-22, Thermosciences Division, Department of Mechanical Engineering, Stanford University, Stanford, CA

  • Michalke A, Hermann G (1982) On the inviscid instability of a circular jets with external flow. J Fluid Mesh 114:343

    Article  MATH  Google Scholar 

  • Orlanski I (1976) A simple boundary condition for unbounded flows. J Comput Phys 21:251–269

    Article  MATH  Google Scholar 

  • Parekh DE, Leonard A, Reynolds WC (1988) Bifurcating jets at high Reynolds numbers. Report TF-35, Thermosciences Division, Department of Mechanical Engineering, Stanford University, Stanford, CA

  • Suzuki H, Kasagi N, Suzuki Y (2004) Active control of an axisymmetric jet with distributed electromagnetic flap actuators. Exp Fluids 36:498–509

    Article  Google Scholar 

Download references

Author information

Authors and Affiliations

  1. Department of Mechanical Engineering, Indian Institute of Technology Kanpur, Kanpur, 208016, India

    Trushar B. Gohil, Arun K. Saha & K. Muralidhar

Authors
  1. Trushar B. Gohil
    View author publications

    You can also search for this author in PubMed Google Scholar

  2. Arun K. Saha
    View author publications

    You can also search for this author in PubMed Google Scholar

  3. K. Muralidhar
    View author publications

    You can also search for this author in PubMed Google Scholar

Corresponding author

Correspondence to Arun K. Saha.

Rights and permissions

Reprints and permissions

About this article

Cite this article

Gohil, T.B., Saha, A.K. & Muralidhar, K. Control of flow in forced jets: a comparison of round and square cross sections. J Vis 13, 141–149 (2010). https://doi.org/10.1007/s12650-009-0020-7

Download citation

  • Received:

  • Accepted:

  • Published:

  • Issue Date:

  • DOI: https://doi.org/10.1007/s12650-009-0020-7

Keywords

Search

Navigation