Uluslararası hakemli dergilerde yayınlanan makaleler

·         A. I. Ruban, and I. Turkyilmaz, (2000) "On laminar separation at a corner point in transonic flow", J. Fluid Mech., Vol. 423, pp. 345--380. (Abstract.)

·         Türkyılmaz, I. (2004) "An investigation of separation near corner points in transonic flow", J. Fluid Mech., vol. 508, pp. 45-70. (Abstract.)

·         Camcı, U. and Türkyılmaz, I. (2004) "Ricci collineations in perfect fluid Bianchi V spacetime", Gen. Relativity Gravitation, vol. 36, no. 9, pp. 2005—2019.

·         Turkyilmaz I. (2010) Incipient separation over wall irregularities in transonic flow, Applied Mathematical Modelling, Vol. 34 (6), pp. 1549-1558.

·         Turkyilmaz I. (2010) An investigation of transonic flow over axisymmetric rigid body, Computers & Fluids, vol. 39 (4), pp. 722-728.

 

Uluslararası bilimsel toplantılarda sunulan ve bildiri kitabında (Proceedings) basılan bildiriler

·         Ruban, A.I. and İ. Türkyılmaz, (1999) “On laminar separation at a corner point in transonic flow”, British Applied Mathematics Colloquium, Bath, UK.

·         Türkyılmaz, İ. and A.I. Ruban (2000) “Analysis of the high Reynolds number transonic flows near corners”, British Applied Mathematics Colloquium, Manchester, UK

·         Ruban, A.I. and İ. Türkyılmaz (2000) ”On laminar separation from a corner point of a rigid body contour in transonic flow”, International Congress of the International Union of Theoretical and Applied Mechanics, in Chicago, Illinois, USA.

·         Türkyılmaz, İ. and A.I. Ruban (2001) “An analysis of the transonic boundary layer separation near corner”, British Applied Mathematics Colloquium, Reading, UK.

·         Ruban, A.I. Türkyılmaz, I. And Buldakov E.V. (2002) “Viscous-inviscid interaction and boundary-layer separation in transonic flow”, Symposium Transsonicum IV, DLR Göttingen, Germany.

·         Türkyılmaz İ, (2006) Transonik Akışın Yüzey Düzensizlikleri Üzerinde Matematiksel incelemesi, XIX. Ulusal Matematik Sempozyumu, 21-25 Ağustos 2006, Dumlupınar Üniversitesi, Kütahya.

·         Turkyilmaz I (2009) An Investigation of Transonic Flow over Axisymmetric Rigid Body, 5th International Advanced Technologies Symposium, May 13-15, 2009, Karabük University, Karabük, Turkey.

On laminar separation at a corner

point in transonic flow.

Abstract

The separation of the laminar boundary layer from a convex corner on a rigid body contour in transonic flow is studied based on the asymptotic analysis of the Navier-Stokes equations at large values of the Reynolds number. It is shown that the flow in a small vicinity of the separation point is governed, as usual, by strong interaction between the boundary layer and inviscid part of the flow. Outside the interaction region the Karman-Guderley equation describing transonic inviscid flow admits a self-similar solution with the pressure on the body surface being proportional to the cubic root of the distance from the separation point. Analysis of the boundary layer driven by this pressure shows that as the interaction region is approached the boundary layer splits into two parts, the near-wall viscous sublayer and the main body of the boundary layer where the flow is locally inviscid. It is interesting that contrary to what happens in subsonic and supersonic flows, the displacement effect of the boundary layer is primarily due to the inviscid part. The contribution of the viscous sublayer proves to be negligible to the leading order. Consequently, the flow in the interaction region is governed by the inviscid-inviscid interaction. To describe this flow one needs to solve the Karman-Guderley equation for the potential flow region outside the boundary layer; the solution in the main part of the boundary layer was found in an analytical form, thanks to which the interaction between the boundary layer and external flow might be expressed via the corresponding boundary condition for the Karman-Guderley equation. Formulation of the interaction problem involves one similarity parameter which in essence is the Karman-Guderley parameter suitably modified for the flow at hand. The solution of the interaction problem has been constructed numerically.

An investigation of separation near

corner points in transonic flow.

Abstract

The incipient of separation from a corner in steady two-dimensional transonic flow has been studied based on viscous-inviscid interaction at high Reynolds number. Of particular interest is to investigat dependence of the critical deflection angle (when a well attached flow turns into a separated flow) on the Karman-Guderley parameter which characterizes of the local flow field. In accordance with the procedure adopted, the analysis of the flow starts with the analysis of the boundary layer and then the solution of the Karman-Guderley equation describing the inviscid part of the flow near the corner point has been investigated. The analysis of the inviscid transonic flow has been performed based on the hodograph method and new solutions have been obtained corresponding to the present flow topologies. In these solutions, the transonic flow appears to be subsonic everywhere except at the sonic corner point. Then, the interaction problem has been formulated using the triple-deck model. Lastly, a procedure based on a semi-direct solution of the governing equations using Newton iterations has been developed to obtain the numerical solution of the interaction problem.

 

An investigation of transonic flow over

axisymmetric rigid body

Abstract

 

The aim of this study is to investigate transonic flow over the axisymmetric rigid body of revolutions using matched asymptotic expansions of high Reynolds number flow. For this purpose the triple-deck model is employed. It allows to study the flow separation near a junction line where a circular cylinder is connected to a divergent conical body. It is found that in the axisymmetric transonic flow the interaction region is governed by the viscous–inviscid interaction process, where the axisymmetric Karman–Guderley equation in the inviscid part of the flow should be coupled with Prandtl’s boundary layer equations for the viscous sublayer. The coupled governing equations of the interaction region is solved using a semi-direct numerical method considering proper boundary conditions. Numerical results imply that incipience of separation may appear over the axisymmetric rigid body subject to body shape and transonic axisymmetric nature makes the flow much less prone to separation as compared to the two-dimensional flow.

 

Incipient separation over wall irregularities

in transonic flow

 

Abstract

 

Incipient separation over wall irregularities in a steady two dimensional flow field of a perfect fluid which has transonic speed characteristics has been investigated considering viscous- inviscid interactions at high Reynolds number. The aim of this work is to investigate dependence of the critical hump height (when a well attached flow over rigid body surface turns into a separated one) on the Karman–Guderley parameter which characterizes of the local flow field. The analysis of the flow field starts with the so-called inspection analysis of the flow properties and then the interaction problem has been constructed using the asymptotic analysis of triple-deck structure of interaction region. Finally, a method based on a semi-direct solution of governing equations of the transonic interaction problem has been used to obtain the numerical solution of the problem.