Discrete Droplet Spray Modeling with Adaptive Mesh Refinement

1
Discrete Droplet Spray Modeling with Adaptive
Mesh Refinement

• Lewis and Clark College
• May 3, 2002
• Sara D. Bauman

2
Adaptive Mesh Refinement

• Grids
• Structured and Uniform
• Logically Rectangular

• Recursively superimposed
• Properly level nested

3
AMR Review (cont.)
Responds to the development of the solution

• Refinement
• Refines grid cell size and timestep
• Refines by multiples of 2
• Refinement criteria
• Error estimation
• Feature Detection
• Fluid field magnitude
• Fluid field gradients

4
AMR Review (cont.)

• Solution Advance
• Time step advance is performed recursively
• Each grid is advanced independently
• Fine grid solutions take precedence over coarse
  grid solutions

5
AMR Fluid Code
Lawrence Berkeley National Laboratories Center
for Computational Science and Engineering (Under
continual development)

• Characteristics
• Navier-Stokes code
• Multi-dimensional
• Low Mach number
• 2nd order accurate

• Rectangular domains
• Capable of parallel computations
• Combination of C and Fortran

6
Data Structure
Bndlst
Inlst
Wrklst
Level lists
Lvlst1
Lvlst0
7
Equation of Motion Tests
 
     
 

g
8
Equation of Motion Tests (cont.)
 
 
     

9
Momentum Conservation
 
 
     
     

10
Turbulence Tests
 
 
3 sec
1 sec
     
     

7 sec
5 sec
11
Evaporation Tests
 
 
 
 

     
     

Squared Radius
time
12
Mass/Energy Conservation
 
 
 
 
     
     

13
KIVA Collision Model
Radial Grid
Cartesian Grid
Pictures from draft of Schmidt and Rutland s NTC
paper for JCP
14
Collision Model Comparison

Relative Error ()
Number of Particles
15
Local Fluid State
Bilinear Interpolation
16
Source Term Distribution
Single Grid / Grid Interior
17
Source Term Distribution
18
Adaptivity Tests


 
 

19
Non-Evaporation Test Case

20
Evaporation Test Case
21
Convergence Rate
2nd Order Preserved!
22
2-D and 3-D Sprays
2-D
3-D
23
Collision Grid Effects

• As grid size decreases
• Number of collision cells increases
• Number of particles decreases
• SMR increases

24
Collision Grid Effects (cont.)
Decreasing collision grid size
25
Refinement Effects - Penetration
Penetration (m)
Time (s)
26
Refinement Effects - Appearance
Fixed
Collision Grid
Refined
27
Turbulence Tests (cont.)
 
 
     
     

Mean Travel
28
Proximity Collision Model
rcoll
29
Collision w/ Adaptation
30
Domain Depth (2-D)
1 m
dxeff
31
Symmetry