Hello, A change in allocation has been requested: Requester: dduke (Daniel Duke) Project: XRayFuelSpray Title: Fuel Injection and Sprays Studied Using X-Ray Diagnostics Description: Computational Fluid Dynamics using the OpenFOAM framework has been employed to simulate cavitating turbulent fluid flow in both simplified nozzles and diesel fuel injectors, with the purpose of supporting and informing x-ray radiography and phase-contrast measurements performed at the Advanced Photon Source. A number of state-of-the-art numerical solvers have been implemented in OpenFOAM; namely incompressible-liquid and fully compressible homogeneous relaxation cavitation models and more recently a noncondensible-gas fully compressible homogeneous relaxation cavitation model. These codes were developed by Schmidt et al at the University of Massachusetts-Amherst. In the last year, we have switched from using OpenFOAM’s built-in solvers for multiphase flow to a dedicated cavitation code (HRMFoam) developed by Professor David Schmidt. The homogeneous relaxation model (HRM) assumes that when vapor is present, the vapor and liquid are homogeneously mixed within the local cell, but are not at thermodynamic equilibrium. The equilibrium state is not computed using an equation of state but is instead determined from a lookup table formulated using NIST REFPROP data. The HRM model has successfully been employed to simulate the effect of varying gasoline-ethanol blended fuels in a cavitating polycarbonate nozzle, and the results were favorably compared to x-ray radiography measurements performed at the Advanced Photon Source. Further high-resolution large eddy simulations of the polycarbonate nozzles used at APS are need to be undertaken in the following year. Scalability of HRMFoam simulations is good up to approx. 72 processors (the capacity of our dedicated nodes). We need to run multiple simulations at various boundary conditions, thus the need for additional allocation beyond the use of the dedicated nodes. Several improved solvers are currently under development which over the next year will allow for the modeling of a non-condensible gas phase, to simulate the difference between a ‘submerged’ cavitating flow and a cavitating flow issuing into a gaseous environment, as is the case for fuel injection in engines. Compressible modeling is also being investigated through both HRM and also alternative compressible fluid solvers. Currently, HRM assumes the liquid phase to be incompressible. Although this has shown good results in comparison with experimental data, given the extremely high pressures involved in fuel injection (greater than 1500 bar) bulk compressibility of the fuel will not be insignificant. Further development is occurring within the OpenFOAM framework and we do not expect to need any additional software installed on Fusion to achieve these goals. Our allocation for the following year will need to be maintained at the current level to achieve the above goals. No increase in allocation is required. We expect that less than 1% of the allocation will be single-core jobs (of which most are file I/O and cleanup tasks at the start and end of parallel jobs). Current: undetermined amount Justification: 6*12 processor dedicated nodes have been purchased on FUSION to support these studies. Requested: 60000 A specific reason has been given: Our group has had to take on a new staff member at rather short notice who is going to be using the LCRC account. He needs to get started doing simulations right away, but there is not enough allocation in our project bank to accommodate his work before the next years' allocations are made.We require an increase in the number of core-hours on Blues/Fusion to see us through to October. Right now, our project (XRayFuelSpray) has about 79k core hours remaining, and we need an extra 60k so that our new group member can do his simulations. If this is not possible, then any smaller amount would still be helpful. In the previous quarter, we didn't use our complete allocation due to staffing changes and other disruptions to our group's activities. This quarter, we are overstretched and will exceed our allocation. We intend to provide a justification in our next proposal for the need to increase our allocation to accommodate our new group members' work. The nature of the additional w ork will involve simulations of natural gas fuel injection systems using Converge software; these simulations will support our research program at APS. If you require further information please contact Daniel Duke ([email protected]) and we will be happy to provide it. This needs to be approved and the final allocation amount decided upon. Thank You, The LCRC Accounts System