An iterative boundary element method for a wing-in-ground effect

Kinaci, Omer Kemal The Society of Naval Architects of Korea 2014 International Journal of Naval Architecture and Oc Vol.6 No.2

In this paper, an iterative boundary element method (IBEM) was proposed to solve for a wing-in-ground (WIG) effect. IBEM is a fast and accurate method used in many different fields of engineering and in this work; it is applied to a fluid flow problem assessing a wing in ground proximity. The theory and the developed code are validated first with other methods and the obtained results with the proposed method are found to be encouraging. Then, time consumptions of the direct and iterative methods were contrasted to evaluate the efficiency of IBEM. It is found out that IBEM dominates direct BEM in terms of time consumption in all trials. The iterative method seems very useful for quick assessment of a wing in ground proximity condition. After all, a NACA6409 wing section in ground vicinity is solved with IBEM to evaluate the WIG effect.

On Propeller Performance of DTC Post-Panamax Container Ship

Kinaci, Omer Kemal,Kukner, Abdi,Bal, Sakir Korean Society of Ocean Engineers 2013 International journal of ocean system engineering Vol.3 No.2

The propeller performance has been investigated using a benchmark Duisburg Test Case ship with RANSE. First, the hydrodynamic characteristics of propeller in case of open water have been analyzed by a commercial CFD program and the results are compared with those of experimental data. Later, the flow around the bare hull has been solved and the frictional resistance value and form factor of the ship have been obtained and compared with those of ITTC57 formulation and experimental results for validation. The free surface effect has been ignored. A good agreement has been obtained between the results of RANSE and experiments at both stages. Then the ship - propeller interaction problem was solved by RANSE and the differences in thrust, torque and efficiency of propeller as compared with the open-water numerical results have been discussed.

A numerical parametric study on hydrofoil interaction in tandem

Kinaci, Omer Kemal The Society of Naval Architects of Korea 2015 International Journal of Naval Architecture and Oc Vol.7 No.1

Understanding the effects of the parameters affecting the interaction of tandem hydrofoil system is a crucial subject in order to fully comprehend the aero/hydrodynamics of any vehicle moving inside a fluid. This study covers a parametric study on tandem hydrofoil interaction in both potential and viscous fluids using iterative Boundary Element Method (BEM) and RANSE. BEM allows a quick estimation of the flow around bodies and may be used for practical purposes to assess the interaction inside the fluid. The produced results are verified by conformal mapping and Finite Volume Method (FVM). RANSE is used for viscous flow conditions to assess the effects of viscosity compared to the inviscid solutions proposed by BEM. Six different parameters are investigated and they are the effects of distance, thickness, angle of attack, chord length, aspect ratio and tapered wings. A generalized 2-D code is developed implementing the iterative procedure and is adapted to generate results. Effects of free surface and cavitation are ignored. It is believed that the present work will provide insight into the parametric interference between hydrofoils inside the fluid.

A Method of Moments Approach for Laminar Boundary Layer Flows

Kinaci, Omer Kemal,Usta, Onur Korean Society of Ocean Engineers 2013 International journal of ocean system engineering Vol.3 No.3

Blasius equation describes the boundary layer formed over a flat plate inside a fluid and this equation is solved numerically by the method of moments which is a type of weighted residual methods. Compared to the traditionally used Runge - Kutta Method, Method of Moments propose a direct solution to Blasius Equation which makes it easier to solve. The obtained solutions show good agreement with the results found in literature and this study aims to demonstrate the power of the method.

Does the abdominal ultrasonography reliable in the diagnosis of postoperative pancreatic fistula after pancreaticoduodenectomy in the first postoperative week?

Erdem Kinaci,Mert Mahsuni Sevinc,Savas Bayrak,Ceyda Turan Bektas,Aytul Hande Yardimci,Abdulkerim Ozakay 대한외과학회 2016 Annals of Surgical Treatment and Research(ASRT) Vol.91 No.5

Purpose: We evaluated the efficacy of ultrasonography (US) in the early postoperative period after pancreaticoduodenectomy (PD) to diagnose postoperative-pancreatic-fistula (POPF). Early diagnosis is important to prevent POPF-dependent mortality after PD. The value of radiological modalities for early diagnosing POPF is not clear. Methods: Forty-five patients who underwent transabdominal-US in the first postoperative week after PD were retrospectively evaluated. Two types of grouping methods were performed. Firstly, peripancreatic or perianastomotic fluid collections at least 2 cm in diameter were considered to be a primary positive result on US. Patients then divided into 2 groups: group 1, US-positive and group 2, US-negative. Secondly, to increase the power of US, in addition to primary positive results, the presence of fever, leukocytosis or hyperamylasemia was considered to be a secondary positive result (group 1S). The remaining patients were considered to have secondary negative results (group 2S). The sensitivity and specificity for both grouping methods were calculated for the diagnosis of PF and clinically important PF (ciPF), according to the International Study Group on Pancreatic Fistula criteria. Results: For the first grouping method, the sensitivity was 36% and 28% and the specificity was 80% and 85% for PF and ciPF, respectively. For the second grouping method, the sensitivity was 36% and 29% and the spesificity was 74% and 81% for PF and ciPF, respectively. The unloculated fluid collections were not related to a significant increase in the risk of POPF (P = 0.694). Conclusion: Abdominal-US has low sensitivity and high specificity for the early diagnosis of POPF after PD.

An iterative boundary element method for a wing-in-ground effect

Omer Kemal Kinaci 대한조선학회 2014 International Journal of Naval Architecture and Oc Vol.6 No.2

In this paper, an iterative boundary element method (IBEM) was proposed to solve for a wing-in-ground (WIG) effect. IBEM is a fast and accurate method used in many different fields of engineering and in this work; it is applied to a fluid flow problem assessing a wing in ground proximity. The theory and the developed code are validated first with other methods and the obtained results with the proposed method are found to be encouraging. Then, time consumptions of the direct and iterative methods were contrasted to evaluate the efficiency of IBEM. It is found out that IBEM dominates direct BEM in terms of time consumption in all trials. The iterative method seems very useful for quick assessment of a wing in ground proximity condition. After all, a NACA6409 wing section in ground vicinity is solved with IBEM to evaluate the WIG effect.

A numerical parametric study on hydrofoil interaction in tandem

Omer Kemal Kinaci 대한조선학회 2015 International Journal of Naval Architecture and Oc Vol.7 No.1

Understanding the effects of the parameters affecting the interaction of tandem hydrofoil system is a crucial subject in order to fully comprehend the aero/hydrodynamics of any vehicle moving inside a fluid. This study covers a parametric study on tandem hydrofoil interaction in both potential and viscous fluids using iterative Boundary Element Method (BEM) and RANSE. BEM allows a quick estimation of the flow around bodies and may be used for practical purposes to assess the interaction inside the fluid. The produced results are verified by conformal mapping and Finite Volume Method (FVM). RANSE is used for viscous flow conditions to assess the effects of viscosity compared to the inviscid solutions proposed by BEM. Six different parameters are investigated and they are the effects of distance, thickness, angle of attack, chord length, aspect ratio and tapered wings. A generalized 2-D code is developed implementing the iterative procedure and is adapted to generate results. Effects of free surface and cavitation are ignored. It is believed that the present work will provide insight into the parametric interference between hydrofoils inside the fluid.