Improvements of Fast Fluid Dynamics for Simulating Air Flow in Buildings
09 Nov 2012-Numerical Heat Transfer Part B-fundamentals (Taylor & Francis Group)-Vol. 62, Iss: 6, pp 419-438
TL;DR: In this article, the authors developed two-dimensional fast fluid dynamics (2-D FFD) into three-dimensional FFD (3-D FDFD) for real-time indoor air-flow simulations.
Abstract: Fast fluid dynamics (FFD) can potentially be used for real-time indoor air-flow simulations This study developed two-dimensional fast fluid dynamics (2-D FFD) into three-dimensional fast fluid dynamics (3-D FFD) The implementation of boundary conditions at the outlet was improved with a local mass conservation method A near-wall treatment for the semi-Lagrangian scheme was also proposed This study validated the 3-D FFD with five flows that have features of indoor air flow The results show that the 3-D FFD can successfully capture the three dimensionality of air-flow and provide reliable and reasonably accurate simulations for indoor air flows with a speed of about 15 times faster than current computational fluid dynamics (CFD) tools
Citations
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TL;DR: In this article, the authors implemented fast fluid dynamics (FFD) in Open Field Operation and Manipulation and used a local searching method that made the FFD solver applicable to unstructured meshes.
Abstract: This study implemented fast fluid dynamics (FFD) in Open Field Operation and Manipulation and used a local searching method that made the FFD solver applicable to unstructured meshes. Because the split scheme used in FFD is not conservative, this investigation developed a combined scheme that used a split scheme for the continuity and momentum equations and an iterative scheme for scalar equations. The combined scheme ensures conservation of the scalars. This investigation used two two-dimensional cases and one three-dimensional case, with the experimental data, to test the FFD solver. The predicted results were similar with different types of mesh and numerical scheme and agreed in general with the experimental data.
44 citations
Cites background or methods from "Improvements of Fast Fluid Dynamics..."
...[14] is applicable only to a hexahedral mesh, which cannot provide a sufficiently accurate depiction of a complex geometry such as the occupants of an indoor space....
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...In both methods, the linear interpolation would induce numerical diffusion, but it can be regarded as a substitute for turbulence viscosity and would be helpful in FFD simulation without turbulence models [14]....
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TL;DR: In this article, the authors evaluated four fast fluid dynamics (FFD) models in terms of solving the Navier-Stokes equations, integration with turbulence models, and solving the adjoint equations.
Abstract: The computational fluid dynamics (CFD)-based adjoint method may be appropriate for the inverse design of indoor environments, considering both accuracy and efficiency, but a single design still requires tens of hours with the use of a personal computer. To speed up the inverse design process, this study evaluated four fast fluid dynamics (FFD) models in terms of solving the Navier–Stokes equations, integration with turbulence models, and solving the adjoint equations. This study implemented the FFD solvers in OpenFOAM and validated them for predicting steady-state and transient indoor airflow. This study then validated the FFD solvers for solving the adjoint equations and the FFD-based adjoint method for inverse identification problems and inverse designs in indoor environments. The results showed that FFD was 20 times faster than CFD in predicting transient indoor airflow, and similar computational accuracy could be maintained; the FFD-based adjoint method was 4–16 times faster than the CFD-based adjoint...
44 citations
Cites methods from "Improvements of Fast Fluid Dynamics..."
...After a major development by Stam (1999) in the area of computer games, FFD has been further developed for © 2016 International Building Performance Simulation Association (IBPSA) simulating indoor airflow (Zuo and Chen 2009; Jin, Zuo, and Chen 2012; Xue, Liu, and Zhai 2016; Liu et al. 2016a)....
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TL;DR: In this paper, a coupled dynamic simulation of an indoor environment with heating, ventilation, and air conditioning (HVAC) systems, controls and building envelope heat transfer is presented.
Abstract: This paper describes a coupled dynamic simulation of an indoor environment with heating, ventilation, and air conditioning (HVAC) systems, controls and building envelope heat transfer. The coupled simulation can be used for the design and control of ventilation systems with stratified air distributions. Those systems are commonly used to reduce building energy consumption while improving the indoor environment quality. The indoor environment was simulated using the fast fluid dynamics (FFD) simulation programme. The building fabric heat transfer, HVAC and control system were modelled using the Modelica Buildings library. After presenting the concept, the mathematical algorithm and the implementation of the coupled simulation were introduced. The coupled FFD–Modelica simulation was then evaluated using three examples of room ventilation with complex flow distributions with and without feedback control. Further research and development needs were also discussed.
43 citations
Cites background or methods from "Improvements of Fast Fluid Dynamics..."
...The FFD programme has been validated and used to study various airflows inside and around buildings (Jin, Chen, and Zuo 2013; Jin, Zuo, and Chen 2012a, 2013; Zuo and Chen 2007, 2010b, 2010c)....
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...For the indoor environment simulation, we choose the fast fluid dynamics (FFD) programme (Jin, Zuo, and Chen 2012b; Zuo and Chen 2009) written in the C language....
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...The relatively large discrepancy in prediction at point 5 is due to the complex flow structure that was also discovered in a previous study (Jin, Zuo, and Chen 2012a)....
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TL;DR: A number of backward and forward methods for inverse design and the possibility to reduce the computing costs of CFD-based design methods are discussed.
37 citations
TL;DR: In this article, the authors integrated the models for HVAC systems with coupled multizone and CFD simulations for airflows, using the Modelica simulation platform to improve the computational efficiency.
36 citations
Cites background from "Improvements of Fast Fluid Dynamics..."
...In the literature, both the sequential FFD programs (Zuo and Chen 2009; Jin et al. 2012) and parallel FFD programs (Zuo and Chen 2010; Yang 2013; Tian, Sevilla, and Zuo 2017) are available....
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References
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TL;DR: In this paper, a new technique is described for the numerical investigation of the time-dependent flow of an incompressible fluid, the boundary of which is partially confined and partially free The full Navier-Stokes equations are written in finite-difference form, and the solution is accomplished by finite-time step advancement.
Abstract: A new technique is described for the numerical investigation of the time‐dependent flow of an incompressible fluid, the boundary of which is partially confined and partially free The full Navier‐Stokes equations are written in finite‐difference form, and the solution is accomplished by finite‐time‐step advancement The primary dependent variables are the pressure and the velocity components Also used is a set of marker particles which move with the fluid The technique is called the marker and cell method Some examples of the application of this method are presented All non‐linear effects are completely included, and the transient aspects can be computed for as much elapsed time as desired
5,841 citations
"Improvements of Fast Fluid Dynamics..." refers methods in this paper
...The 3D FFD also applied staggered grid [9] to store velocity on the grid faces and other variables at the grid center as shown in Figure 1....
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TL;DR: In this article, a numerical method for solving incompressible viscous flow problems is introduced, which uses the velocities and the pressure as variables and is equally applicable to problems in two and three space dimensions.
2,797 citations
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TL;DR: This paper proposes an unconditionally stable model which still produces complex fluid-like flows and the stability of the model allows us to take larger time steps and therefore achieve faster simulations.
Abstract: Building animation tools for fluid-like motions is an important and challenging problem with many applications in computer graphics. The use of physics-based models for fluid flow can greatly assist in creating such tools. Physical models, unlike key frame or procedural based techniques, permit an animator to almost effortlessly create interesting, swirling fluid-like behaviors. Also, the interaction of flows with objects and virtual forces is handled elegantly. Until recently, it was believed that physical fluid models were too expensive to allow real-time interaction. This was largely due to the fact that previous models used unstable schemes to solve the physical equations governing a fluid. In this paper, for the first time, we propose an unconditionally stable model which still produces complex fluid-like flows. As well, our method is very easy to implement. The stability of our model allows us to take larger time steps and therefore achieve faster simulations. We have used our model in conjuction with advecting solid textures to create many fluid-like animations interactively in twoand three-dimensions. CR Categories: I.3.7 [Computer Graphics]: Three-Dimensional Graphics and Realism—Animation
1,640 citations
"Improvements of Fast Fluid Dynamics..." refers methods in this paper
...Fast Fluid Dynamics (FFD) is a technique introduced by Stam [7] for computer games, aimed to simulate incompressible fluid flows with a simple and stable approach....
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...1 Governing equations for fast fluid dynamics Fast Fluid Dynamics (FFD) is a technique introduced by Stam [7] for computer games,...
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TL;DR: In this paper, the velocity distribution and reattachment length of a single backward-facing step mounted in a two-dimensional channel were measured using laser-Doppler measurements.
Abstract: Laser-Doppler measurements of velocity distribution and reattachment length are reported downstream of a single backward-facing step mounted in a two-dimensional channel. Results are presented for laminar, transitional and turbulent flow of air in a Reynolds-number range of 70 < Re < 8000. The experimental results show that the various flow regimes are characterized by typical variations of the separation length with Reynolds number. The reported laser-Doppler measurements do not only yield the expected primary zone of recirculating flow attached to the backward-facing step but also show additional regions of flow separation downstream of the step and on both sides of the channel test section. These additional separation regions have not been previously reported in the literature.Although the high aspect ratio of the test section (1:36) ensured that the oncoming flow was fully developed and two-dimensional, the experiments showed that the flow downstream of the step only remained two-dimensional at low and high Reynolds numbers.The present study also included numerical predictions of backward-facing step flow. The two-dimensional steady differential equations for conservation of mass and momentum were solved. Results are reported and are compared with experiments for those Reynolds numbers for which the flow maintained its two-dimensionality in the experiments. Under these circumstances, good agreement between experimental and numerical results is obtained.
1,637 citations
"Improvements of Fast Fluid Dynamics..." refers background in this paper
...[17], at higher Reynolds number, the sidewall of the channel would induce...
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...[17] conducted experimental investigation of backward-facing step flow and high quality data was obtained....
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TL;DR: In this paper, a series of numerical issues related to the analysis and implementation of fractional step methods for incompressible flows are addressed, and the essential results are summarized in a table which could serve as a useful reference to numerical analysts and practitioners.
1,230 citations