Florida State University

1
Physics-Based Boiling Simulation
Florida State University V. Mihalef B. Unlusu D.
Metaxas M. Sussman M. Y. Hussaini
2
Abstract

• ???? Boiling ??? ?????
• ??? ??? ?? ?? ?????
• ?? ???? ?????
• ????(mass transfer) ?? ?????
• ??? ??? ?? ?????
• ?? ??? ??
• Roiling boil
• ?? ???? nucleation seeding

3
Introduction

• ??? gradients ???? ???? ?? ?? ???, ??? ??? ???
  ??? ????? ?
• ???? ??? Navier-Stokes simulator ??
• ??? heat dynamics ? mass transfer mechanism ??
• ????? bubble? ???? ??? ??
• MSKG05 ??? ??? ??

4
Introduction (Cont)

• ?? ?? ?
• physics-based approach
• nucleation site ???? mass transfer ??

flux
facing normal
latent heat of vaporization
coefficient of diffusivity for the temperature

5
Previous Work

• Eulerian ?? grid elements ??
• nodes, cell centers, face centers
• Navier-Stokes solvers FM96
• semi-Lagrangian techniques Sta99
• particle level set method EMF02
• generate impressive bubbles HK05
• multiple interacting fluid LSSF06

6

• Lagrangian methods
• the smooth particle hydrodynamics method (SPH)
• Temperature property to particles MSKG05
• spring-mass system
• modeling heating and melting of deformable
  objects TPF89

7
Previous Work (Cont)

• mass conservation
• PLS method
• Hybrid particle
• CIP method
• color field gradient advect
• CLSVOF method
• PLS ?? ?? ?? Bubble? ???? ???

8
CLSVOF (coupled level set and volume of fluid)
9
CLSVOF

• The level set is updated so that the new liquid
  volume matches the volume fraction F

10
Our Fluid Solver

• Second order extension Sus03
• single-phase ??, ??? ?? ??? ??? ??
• tow-phase ???? ??
• First order two-phase approaches ?? SHS04
• Continuum methods

11
Boundary conditions for nucleation sites

• Bubbles form
• Vortex, rise bubble, fill up emptied space
• nucleation sites
• seeded at an arbitrary frequency

12
Our Fluid Solver

• Mass Transfer
• the level set equation, volume-of-fluid equation

13

• Navier-Stokes equation

14

• material derivative
• initial surface water level
• The density and Heaviside function H

15

• Temperature equation

16

• continuity condition

17
Outline of numerical method for
gas-liquidcoupling

• face centered density
• height fraction

18
Step 1.

• Calculate mass transfer rate

19
Step 2.

• update and F due to mass transfer

20
Step 3.

• calculate provisional advective states

material (advective) derivative
21
Step 4.

• temperature diffusion,

The discretization of a Poisson equation
GFCK02.
22
Step 5.

• velocity diffusion, LRR00

The face centered viscosity is defined as,
The velocity is defined as,
23
Step 6.

• update of surface tension, gravity and viscous
  terms at the cell faces,

24
Step 7.

• pressure correction step.

Heaviside function is defined as,
25
Step 8. 9.

• update the density and height fractions using the
  current values of the level sets
• update the global velocity
• set the liquid and gas velocity
• extrapolate the liquid velocity

26
Animations

• using an Athlon 64 workstation with 2.4GHz and
  3GB RAM
• simulations evolved to very energetic boiling,
• decrease in the liquid-level during boiling.
• bubbles burst when they reach the liquid surface
• mass is transferred to the air

27
Animations

• Circulation
• bubbles rise to the surface naturally

Small viscosity mixing pattern
Large viscosity "straight" pattern
28
Animations

• The boiling became very energetic, with lots of
  circulation, what one would call a roiling boil.

29
Animations

• Interactions with heated objects

The sphere temperature is 500 K before t2.5 and
300 K afterwards
30
Conclusion

• Modeling and simulating boiling-type phenomena
• Using two-phase flow formulation of the CLSVOF
  method
• Future journal paper
• two-way interactions with heated deformable
  objects