Klaus Schönfeld - Academia.edu (original) (raw)
Papers by Klaus Schönfeld
Physics Letters B, 1990
The transverse momentum distribution of (anti)quarks created in the chromo-electric field of an i... more The transverse momentum distribution of (anti)quarks created in the chromo-electric field of an infinitely long hadronic flux tube is derived. The effects of the finite radius of the hadronic strings on their fragmentation are studied simulating e+e-annihilation events in the framework of a dynamical string model that contains two parameters: the string tension x=0.89 GeV/fm (determined by the Regge slope), and the radius of the string. It is shown that a string radius of about 0.5 fm allows Io describe successfully both the width of the transverse momentum distribution in the low-px region and the multiplicities.
Modern Physics Letters A, 1993
The microscopic phase space approach RQMD1 is used to investigate the stopping power of very heav... more The microscopic phase space approach RQMD1 is used to investigate the stopping power of very heavy nuclei at collider energies. We find no gap in the rapidity distribution around mid-rapidity even at RHIC energies [Formula: see text], but rather strong filling of the mid-rapidity region. Neither is there a broad plateau for secondaries nor are the correlations between space-time and momentum as strong as in the Bjorken-McLarren scenario. This renders the Bjorken picture questionable at these energies for systems of combined mass A ≈ 400.
Large eddy simulation (LES) techniques are often presented today as the ideal tool to address com... more Large eddy simulation (LES) techniques are often presented today as the ideal tool to address combustion instabilities problems. Combustion instabilities have been studied for a long time (Crocco 1956, 1969, Poinsot and Candel 1988, Candel et al. 1996), but their prediction during the design process of real systems remains extremely difficult. The recent progress of direct numerical simulations (DNS) (Poinsot, Candel and Trouvé 1996) and of LES for reacting flows (Veynante and Poinsot 1997) suggests that such prediction should be easier in the near future. One important reason for this is the fact that very large scale structures control combustion instabilities (Poinsot et al. 1987); for these scales, LES should perform better than for 'stable' turbulent combustion (Bray et al. 1989, Baum et al. 1994) where an extended range of eddies has to be resolved to characterize the turbulence/chemistry interaction. To develop LES techniques for realistic computations of combustion instabilities, the following issues must be addressed: • LES models must be developed both for the flow and for the flow/chemistry interaction. These goals are the center of current research efforts (Menon and
International Journal for Numerical Methods in Fluids, 2002
A methodology to prescribe integral boundary conditions is proposed. The approach makes use of th... more A methodology to prescribe integral boundary conditions is proposed. The approach makes use of the decomposition of the solution into waves. It applies to any numerical method solving hyperbolic equations, including the compressible Navier-Stokes equations or their incompressible counterpart when solved through an artiÿcial compressibility method. For any physical quantity to be imposed (e.g. the mass ow rate entering the computational domain), the boundary treatment consists in imposing a 1D incoming 'acoustic' wave proportional to the di erence between the mean quantity of interest (e.g. the mean mass ow rate) over the boundary and its prescribed target value. The approach is validated by computing both steady and pulsated channel ows for Womersley number upto 15. Results from a 3D simulation of the blood ow within a human aortic arch are brie y discussed. Copyright ? 2002 John Wiley & Sons, Ltd.
Schriftliche Hausarbeit, 2019
Physics Letters B, 1990
The transverse momentum distribution of (anti)quarks created in the chromo-electric field of an i... more The transverse momentum distribution of (anti)quarks created in the chromo-electric field of an infinitely long hadronic flux tube is derived. The effects of the finite radius of the hadronic strings on their fragmentation are studied simulating e+e-annihilation events in the framework of a dynamical string model that contains two parameters: the string tension x=0.89 GeV/fm (determined by the Regge slope), and the radius of the string. It is shown that a string radius of about 0.5 fm allows Io describe successfully both the width of the transverse momentum distribution in the low-px region and the multiplicities.
Modern Physics Letters A, 1993
The microscopic phase space approach RQMD1 is used to investigate the stopping power of very heav... more The microscopic phase space approach RQMD1 is used to investigate the stopping power of very heavy nuclei at collider energies. We find no gap in the rapidity distribution around mid-rapidity even at RHIC energies [Formula: see text], but rather strong filling of the mid-rapidity region. Neither is there a broad plateau for secondaries nor are the correlations between space-time and momentum as strong as in the Bjorken-McLarren scenario. This renders the Bjorken picture questionable at these energies for systems of combined mass A ≈ 400.
Large eddy simulation (LES) techniques are often presented today as the ideal tool to address com... more Large eddy simulation (LES) techniques are often presented today as the ideal tool to address combustion instabilities problems. Combustion instabilities have been studied for a long time (Crocco 1956, 1969, Poinsot and Candel 1988, Candel et al. 1996), but their prediction during the design process of real systems remains extremely difficult. The recent progress of direct numerical simulations (DNS) (Poinsot, Candel and Trouvé 1996) and of LES for reacting flows (Veynante and Poinsot 1997) suggests that such prediction should be easier in the near future. One important reason for this is the fact that very large scale structures control combustion instabilities (Poinsot et al. 1987); for these scales, LES should perform better than for 'stable' turbulent combustion (Bray et al. 1989, Baum et al. 1994) where an extended range of eddies has to be resolved to characterize the turbulence/chemistry interaction. To develop LES techniques for realistic computations of combustion instabilities, the following issues must be addressed: • LES models must be developed both for the flow and for the flow/chemistry interaction. These goals are the center of current research efforts (Menon and
International Journal for Numerical Methods in Fluids, 2002
A methodology to prescribe integral boundary conditions is proposed. The approach makes use of th... more A methodology to prescribe integral boundary conditions is proposed. The approach makes use of the decomposition of the solution into waves. It applies to any numerical method solving hyperbolic equations, including the compressible Navier-Stokes equations or their incompressible counterpart when solved through an artiÿcial compressibility method. For any physical quantity to be imposed (e.g. the mass ow rate entering the computational domain), the boundary treatment consists in imposing a 1D incoming 'acoustic' wave proportional to the di erence between the mean quantity of interest (e.g. the mean mass ow rate) over the boundary and its prescribed target value. The approach is validated by computing both steady and pulsated channel ows for Womersley number upto 15. Results from a 3D simulation of the blood ow within a human aortic arch are brie y discussed. Copyright ? 2002 John Wiley & Sons, Ltd.
Schriftliche Hausarbeit, 2019