We show that the coupled continuum pipe flow model (CCPF) for flows in karst aquifers is ill-posed in the sense that no reasonable solution exists. We also demonstrate that Hua’s modified CCPF model is ill-posed in 3D although it is well-posed in two spatial dimensions. A new modification of the original CCPF model that is consistent with basic physics is proposed and its well-posedness is prov...

complex culverts have a change of section (transition) at one or more positions along their lengths. the hydraulic performance cannot be estimated using simple culvert methods because the transition may change the control point. by modeling the flow through a transition as free flow, sluice flow, pipe flow and treating a complex culvert, as a series of simple culverts with the appropriate hydra...

Gallium nitride (GaN) high-electron-mobility transistors (HEMTs) dissipate high power densities which generate hotspots and cause thermomechanical problems. Here, we propose and simulate GaN-based HEMT technologies that can remove power densities exceeding 30 kW/cm at relatively low mass flow rate and pressure drop. Thermal performance of the microcooler module is investigated by modeling both ...

there is different methods for simulating river flow. some of thesemethods such as the process based hydrological models need multiple input data and high expertise about the hydrologic process. but some of the methods such as the regression based and artificial inteligens modelsare applicable even in data scarce conditions. this capability can improve efficiency of the hydrologic modeling in u...

The current offshore oil & gas multi-phase production and transportation installations have big challenges related with the slugging flow: An unstable multi-phase flow regime where the flow rates, pressures and temperatures oscillate in the considered processes. Slug can be caused by different operating conditions and installation structures. The most severe slugs are often induced in long vert...

Simulation is considered to be a method to improve planning and control efficiency in the field of logistics. In our view no existing simulation tool meets the basic requirements sufficiently. We therefore developed a new simulator with the following characteristics: • Simulation principles: General purpose discrete event simulator. • Modeling basis: Meta model comprising few specific basic ele...

in this paper, the problem of turbulent forced convection flow of water- alumina nanofluid in a uniformly heated pipe has been thoroughly investigated. in numerical study, single and two-phase models have been used. in single-phase modeling of nanofluid, thermal and flow properties of nanofluid have been considered to be dependent on temperature and volume fraction. effects of volume fraction a...

the main objective in this paper is creating a method for one-dimensional modeling of multi stage axial flow turbine. the calculation used in this technique is based on common thermodynamics and aerodynamics principles in a mean stream line analyses. in this approach, loss models have to be used to determine the entropy increase across each section in the turbine stage. finally, the analysis an...

changes of hydrodynamic parameters in microchannel branches affect the suspended biological samples in blood. to prevent denaturation and hemolysis, we have numerically investigated the effect of divergence angle on shear rate and velocity at branch entrance (discharge rate), under electroosmotic flow. in such flow, hydrodynamic properties are also affected by zeta potential at the microchannel...

In this study, direct numerical simulation for the bubble condensation in the subcooled boiling flow was performed. The main goal was to develop the CFD modeling for the bubble condensation and to evaluate the accuracy of the VOF model with the developed CFD modeling. CFD modeling for the bubble condensation was developed by modeling the source terms in the governing equations of VOF model usin...