Browsing by Author "Baranoğlu, B."
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Item Open Access Boundary-Element method in microfluidics(Springer, New York, 2015) Çetin, Barbaros; Baranoğlu, B.; Li, D.Item Open Access Isogeometric and NURBS-enhanced boundary element formulations for steady-state heat conduction with volumetric heat source and nonlinear boundary conditions(Elsevier, 2022-12) Gümüş, Özgür Can; Baranoğlu, B.; Çetin, BarbarosBoundary Element Method (BEM) is a numerical tool that is applied to many different types of engineering problems. BEM possesses several advantages over other numerical methods such as boundary-only discretization and its semi-analytical nature. Application of Isogeometric Analysis (IGA) to BEM is a recently proposed computational method where the main purpose is to use geometrical basis functions as the shape functions of field variables. Key features of combining these two techniques are the exact representation of the geometry, elimination or suppression of the meshing procedure, reduction of the problem dimension and obtaining highly accurate results especially for the flux values on the boundaries compared to conventional BEM. In this study, steady-state heat conduction problems with nonlinear boundary condition and surface heat source are analyzed where geometries are formed by NURBS, and field variables are described with Lagrangian (constant and quadratic) basis functions and NURBS basis functions. Convergence rates and CPU time of different types of element representations are discussed which eventually reveals the performance and capabilities of IGABEM.Item Open Access Modeling of dielectrophoretic particle motion: Point particle versus finite‐sized particle(Wiley - V C H Verlag GmbH & Co. KGaA, 2017-02-06) Çetin B.; Öner, D. S.; Baranoğlu, B.Dielectrophoresis (DEP) is a very popular technique for microfluidic bio‐particle manipulation. For the design of a DEP‐based microfluidic device, simulation of the particle trajectory within the microchannel network is crucial. There are basically two approaches: (i) point‐particle approach and (ii) finite‐sized particle approach. In this study, many aspects of both approaches are discussed for the simulation of direct current DEP, alternating current DEP, and traveling‐wave DEP applications. Point‐particle approach is implemented using Lagrangian tracking method, and finite‐sized particle is implemented using boundary element method. The comparison of the point‐particle approach and finite‐sized particle approach is presented for different DEP applications. Moreover, the effect of particle–particle interaction is explored by simulating the motion of closely packed multiple particles for the same applications, and anomalous‐DEP, which is a result of particle–wall interaction at the close vicinity of electrode surface, is illustrated.Item Open Access A multi-domain direct boundary element formulation for particulate flow in microchannels(Elsevier Ltd, 2021-11-01) Topuz, Alper; Baranoğlu, B.; Çetin, BarbarosIn the present study, a multi-domain boundary element formulation is developed for high surface-area-to-volume ratio problems (i.e. particulate flow in high aspect ratio microfluidic channels, in a porous medium or in microfluidic devices with repetitive structures). The solution domain is decomposed into subdomains and the variable condensation technique is implemented. The solution matrices are built for each subdomain, and the matrices are updated at each time step only for the subdomains in which the particles move at each time step. Ghost domains, which are fictitious domains encapsulating the interfaces between the subdomains, are also introduced in the formulation to treat the particles crossing the interfaces between the subdomains. The formulation reveals that the computation of the subdomain matrices is further simplified for solution domains composed of periodic structures. The results of our study revealed that speed-up values as high as 50 is achievable with the current formulation.