- Author
-
McDermott, R. J.
|
Forney, G. P.
|
McGrattan, K. B.
|
Mell, W. E.
- Title
- Fire Dynamics Simulator Version 6: Complex Geometry, Embedded Meshes and Quality Assessment.
- Coporate
- National Institute of Standards and Technology, Gaithersburg, MD
- Book or Conf
- European Conference on Computational Fluid Dynamics, 5th. ECCOMAS CFD 2010. June 14-17, 2010,
Lisbon, Portugal,
Pereira, J. C. F.; Sequeira, A., Editors,
2010
- Keywords
-
simulators
|
geometry
|
fire models
|
turbulence
|
equations
|
formulation
|
storage
|
Reynolds number
|
velocity
|
plumes
- Identifiers
- Fire Dynamics Simulator (FDS); Large-Eddy Simulation (LES); Smokeview (SMV); Immersed Boundary Method (IBM); Smokediff; LES wall models in direct forcing IBM; summary of the wall model IBM method; using lagrangian particles; embedded meshes; embedded mesh method (forward euler version); quality assessment; wavelet error measure
- Abstract
- The Fire Dynamics Simulator (FDS) and Smokeview (SMV) are computational and visualization tools specifically designed for large-eddy simulations (LES) of low-speed, thermally driven ows. FDS Version 6 will offer improvements in the turbulence model (dynamic Smagorinsky), the wall model (Werner Wengle), and the scalar transport scheme (Superbee, CHARM). These features are already in the testing phase. In this work we discuss further developments related to complex geometry, embedded (or nested) mesh methods, and LES quality assessment. In FDS 6, we are developing two new approaches to handling complex geometry that take us beyond the limitations of the current stair-step method. For grid-resolved objects we are developing a complex geometry module with a second-order immersed boundary method capable of utilizing LES wall stress models. For subgrid objects, such as electrical cables or vegetation in wildland fires, we are developing a particle-based approach, similar to a multi-phase droplet formulation, where the gas phase subgrid sources of mass, momentum, and energy are governed by empirical laws for pyrolysis, drag, and heat transfer, respectively. Since LES quality is principally tied to grid resolution, in FDS 6 we introduce an embedded (or nested) mesh strategy which utilizes a staggered grid framework and a fast direct Poisson solver on each mesh block. We are also developing three strategies for quality assessment. The frst is to compute local metrics of resolution such as the local fraction of resolved kinetic energy. A second strategy is to use local wavelet-based error estimators. Finally, with the latest release of Smokeview we have bundled a new executable called Smokediff. With this tool the user can compare results at different grid resolutions or with different model parameters and easily visualize the results.