# Direct numerical simulation of turbulence compressed in a cylinder

## Summary

The behaviour of initially isotropic turbulence during compression in a cylinder is investigated by means of direct numerical simulation (DNS). The flow is governed by the 3D time-dependent Navier-Stokes equations, which have been simplified assuming an adiabatic compression process in which sound waves are unimportant and density, temperature and shear viscosity are functions of time alone. A finite volume technique is used to integrate these equations in a cylindrical coordinate system which is axially compressed while the piston moves. The numerical scheme is central and essentially second-order accurate in space and time. Initial conditions with well correlated velocity and pressure fluctuations according to decaying isotropic turbulence are generated from a stochastic divergence-free velocity field which is made to satisfy a prescribed energy spectrum. Two flow cases with different evolution of the compression rate are considered in order to study its influence on the growth rate of the turbulent kinetic energy. It is found that only the compression ratio (not the rate) has an effect. Furthermore, the simulations show that turbulence cannot be sustained in zones close to the piston surface and the cylinder head.

## Keywords

Turbulent Kinetic Energy Direct Numerical Simulation Cylinder Head Isotropic Turbulence Compression Process## Preview

Unable to display preview. Download preview PDF.

## References

- [1]C.T. Wu, J.H. Ferziger and D.R. Chapman, 1985: Simulation and modeling of homogeneous, compressed turbulence.
*Thermosciences Div. Rept. TF-21*, Mech. Engg. Dept., Stanford University.Google Scholar - [2]U. Schumann, 1975: Subgrid scale model for finite difference simulations of turbulent flows in plane channels and annuli.,
*J. Comp. Physics*,**18**, 376–404.MathSciNetzbMATHCrossRefGoogle Scholar - [3]E. Güntsch and R. Friedrich, 1994: On the influence of compression and rotation on initially isotropic turbulence in a cylinder.,
*Proc. 2nd Europ. Comp. Fluid Dyn. Conf. 5–8 Sept. 1994*, Stuttgart, S. Wagner et al. (Eds), Wiley, New York, pp. 525–534.Google Scholar - [4]E. Güntsch and R. Friedrich, 1995: Compression of initially isotropic turbulence in a cylinder at low Reynolds number.,
*Proc. 10th Symp. on Turb. Shear Flows, Pennstate University, 14–16 August, 1995*.Google Scholar - [5]C. Maaß and U. Schumann, 1996: Direct numerical simulation of separated turbulent flow over a wavy boundary. This volume.Google Scholar
- [6]M. Manhart and H. Wengle, 1996: Large eddy simulation and eigenmode decomposition of turbulent boundary layer over a hemisphere. This volume.Google Scholar
- [7]M. Griebel, W. Huber and C. Zenger, 1996: Numerical turbulence simulation on a parallel computer using the combination method. This volume.Google Scholar
- [8]E. Güntsch, 1996: Kompression isotroper Turbulenz in einem Zylinder. — Eine numerische Studie. Doctoral Dissertation. TU München.Google Scholar
- [9]W.C. Reynolds, 1980: Modeling of fluid motions in engines — An introductory overview. In: J.N. Mattavi and C.A. Amann (Eds.),
*Combustion Modeling in Reciporcating Engines, pp. 11–20*Google Scholar - [10]G. Serre, 1994: Etude Experimental Et Modelisation De La Turbulence Homogene Compressee. Doctoral Dissertation. L’Ecole Central de Lyon.Google Scholar