An on-the-fly mechanism reduction approach is employed in this paper to integrate detailed chemical kinetics with a computational fluid dynamics (CFD) code. The reduction methodology employs an instantaneous element flux analysis to identify redundant species and reactions for given local conditions. The emphasis of this work is focused on the numerical study of homogeneous charge compression i...

Abstract The high speed, transient cavitating flow distribution inside diesel injector nozzles with consideration of the opening and closing needle valve is calculated using a generalized equation of state (EOS) to describe the fluid density, a homogeneous equilibrium model (HEM) for phase change, and an arbitrary moving mesh to account for needle motion. The KIVA-3V code was modified for the g...

A multi-pulse injection strategy for premixed charge compression ignition (PCCI) combustion was investigated in a four-valve, direct-injection diesel engine by a computational fluid dynamics (CFD) simulation using KIVA-3V code coupled with detailed chemistry. The effects of fuel splitting proportion, injection timing, spray angles, and injection velocity were examined. The mixing process and fo...

A computational study of a directinjection (DI) engine intake system using KIVA-3V was conducted. The engine considered had two intake ports designed to generate a swirling motion of the intake charge in the cylinder. To investigate the effect of adding shrouds to the intake valves on swirl, two sets of intake valves were considered; the first set consisted of conventional valves, and the secon...

A new combustion model is developed and applied to simulate combustion in dual-fuel engines in which the premixed natural gas is ignited by the combustion flame initiated by a diesel spray. The model consists of a diesel auto-ignition model and a flame propagation model. A G-equation model previously developed to simulate SI engine combustion was incorporated with an auto-ignition model to simu...

Donation-based crowdfunding platform Kiva seems to hold the promise of peer-to-peer lending with zero interest rate to help the poor. However, it is actually intermediated by microfinance institutions, which raise funds from Kiva lenders, disburse the funds to borrowers and collect high interest. Later Kiva launched another platform Kiva Zip that implements interest-free loans directly from len...

BACKGROUND Vertebral compression fractures (VCFs) are the most common osteoporotic fractures and cause persistent pain, kyphotic deformity, weight loss, depression, reduced quality of life, and even death. Current surgical approaches for the treatment of VCF include vertebroplasty (VP) and balloon kyphoplasty (BK). The Kiva® VCF Treatment System (Kiva System) is a next-generation alternative su...

BACKGROUND Bullying is a major problem worldwide and Chile is no exception. Bullying is defined as a systematic aggressive behavior against a victim who cannot defend him or herself. Victims suffer social isolation and psychological maladjustment, while bullies have a higher risk for conduct problems and substance use disorders. These problems appear to last over time. The KiVa antibullying pro...