Presentation by Bas van Maren, Delft University of Technology, The Netherlands, at the Delft3D - User Days (Day 3: Sediment transport and morphology), during Delft Software Days - Edition 2018. Wednesday, 14 November 2018, Delft.

1. Slurry modelling: development and application of a
non-Newtonian Delft3D-FLOW version
14 November 2018
D.S. van Maren, Luca Sittoni, A.M. Talmon, J.L.J. Hanssen, J.A.Th.M
van Kester, J.C. Winterwerp, E. Parent, A. Mourits, Q. Ye, R.E.
Uittenbogaard, H. van Es

2. What is a non-Newtonian fluid?
- Delft Software Days: 138 presentations & courses
- 99.3% of these were about Newtonian fluids

3. What is a non-Newtonian fluid?
Newtonian fluid: a fluid in which the shear rate depends linearly on
the shear stress (deformation scales linearly with force) because the
fluid viscosity is constant
11 december 2018
viscosity
stress
Stress(Pa)
Shear rate (/s)

4. What is a non-Newtonian fluid?
Newtonian fluid: a fluid in which the shear rate depends linearly on
the shear stress (deformation scales linearly with force) because the
fluid viscosity is constant
11 december 2018
Fluid’sresistance
Force
Force
Response

5. What is a non-Newtonian fluid?
Non-Newtonian fluid: non-lineair relation between the shear rate and
the shear stress, because the fluid viscosity is not constant
(depending on the shear rate OR shear history)
11 december 2018
Viscosity
Stress (Pa)
Shear thinning: decrease
in viscosity with shear
Stress(Pa)
Shear rate (/s)

6. What is a non-Newtonian fluid?
Non-Newtonian fluid: non-lineair relation between the shear rate and
the shear stress, because the fluid viscosity is not constant
(depending on the shear rate OR shear history)
11 december 2018
Shear thickening:
decrease in viscosity
with shear
Viscosity
Stress (Pa)
Stress(Pa)
Shear rate (/s)

7. What is a non-Newtonian fluid?
Non-Newtonian fluid: non-lineair relation between the shear rate and
the shear stress, because the fluid viscosity is not constant
(depending on the shear rate OR shear history)
11 december 2018
Bingham: linear
relation with yield
stress
Viscosity
Stress (Pa)
Stress(Pa)
Shear rate (/s)

8. Examples in hydraulic engineering
slurries

9. Examples in hydraulic engineering
Fluid mud

10. 11 december 2018
Delft3D slurry
o Oil sands industry produce fluid tailings

11. 11 december 2018
Delft3D slurry
o Oil sands industry produce fluid tailings
o These tailings are discharged into basins which should become (in
time) nature again.
o But: these basins do not consolidate and remain fluid  nature
does not recover

12. Delft3D slurry
o Oil sands industry produce fluid tailings
o These tailings are discharged into basins which should become (in
time) nature again.
o But: these basins do not consolidate and remain fluid  nature
does not recover
o Possible solutions:
o Mixing of tailing fluid with sand  increase consolidation rates
o Capping of a tailing basin with sand
o Deltares is developing a non-Newtonian version of Delft3D for the
Canadian mining industry to quantify potential measures /
mitigation efforts

13. Delft3D slurry: modified viscosity
o Replace the vertical eddy viscosity in the 3D momentum equation
by an apparent viscosity
11 december 2018

14. 11 december 2018
Delft3D slurry: modified viscosity
o Replace the vertical eddy viscosity in the 3D momentum equation
by an apparent viscosity
o Compute this apparent viscosity from the shear stress and the
shear rate
a



viscosity stress
2 2
u v
z z

    
    
    

15. 11 december 2018
Delft3D slurry: modified viscosity
o Replace the vertical eddy viscosity in the 3D momentum equation
by an apparent viscosity
o Compute this apparent viscosity from the shear stress and the
shear rate
o Compute the shear stress from material properties (mainly yield
stress & viscosity) and the shear rate
a



2 2
u v
z z

    
    
    
n
y   
stress(Pa)
shear rate (/s)

16. 11 december 2018
Delft3D slurry: modified viscosity
o Replace the vertical eddy viscosity in the 3D momentum equation
by an apparent viscosity
o Compute this apparent viscosity from the shear stress and the
shear rate
o Compute the shear stress from material properties (mainly yield
stress & viscosity) and the shear rate
o Viscosity & yield stress are concentration dependent and material
dependent, requiring
1. a choice of rheology model
2. laboratory experiments for input parameters
n
y   

17. Delft3D slurry: modified settling velocity
o At (very high sediment concentrations, the effective settling
velocity is trapped by grain-grain & grain-fluid interactions
(hindered settling)
Clear water
(high ws)
Turbid water
(low ws)
Slurry
(no ws)

18. 11 december 2018
Delft3D slurry: modified settling velocity
o At (very high sediment concentrations, the effective settling
velocity is trapped by grain-grain & grain-fluid interactions
(hindered settling)
o Mud particles do no settle (gelled bed), but sand particles may
settle due to shear settling
o Shear settling: sand settling velocity resulting from changes in
apparent viscosity (in turn resulting from sheared flow)
Talmon et al., 2018

19. Delft3D slurry: modified settling velocity
o At (very high sediment concentrations, the effective settling
velocity is trapped by grain-grain & grain-fluid interactions
(hindered settling)
o Mud particles do no settle (gelled bed), but sand particles may
settle due to shear settling
o Shear settling: sand settling velocity resulting from changes in
apparent viscosity (in turn resulting from sheared flow)
  2
,0,
,18
s ww w
s sand
w a cf
gd
w
  
 


 , , ,0,sand _
sa_ max
1 1
wm
sa
s eff sand s fl cl saw w

 

 
     
 
Concentration terms
Apparent viscosity

20. Results
discharge point
beach
tailings
pond

21. Results: non-segregating tailings over beach
11 december 2018
1:100 slope, dX = 10m
Release:
- Q = 0.1 m2/s
- 260 kg/m3 carrier fluid
- 450 kg/m3 sand
U [m/s]
c τ u μ ws
depth

22. Results: non-segregating tailings over beach
11 december 2018
1:100 slope, dX = 10m
U [m/s]
▪ Shear stress
increases linearly from
surface to bed
▪ Yield stress is uniform
▪ Transition to plug flow
at intersection: du/dz
= 0
▪ Rapid decrease in
apparent viscosity
▪ Results in increase in
ws
▪ And therefore
decrease in C.
c τ u μ ws
depth

23. Results: non-segregating tailings over beach
11 december 2018
1:100 slope, dX = 10m
U [m/s]
Conclusion:
No segregation of sand &
carrier fluid for this tailing
Next steps: more
complex configurations
c τ u μ ws
depth

24. Results: segregating tailings over beach
Distance along beach  1000 m
Elevation10m
Sandconcentration
SFR
SFR in bed  Fines Capture
~ 14 hours simulation

25. Results: tailings pond
11 december 2018
Yield stress = 2 kPa
Density fines = 1400 kg/m3
Density sand = 1520 kg/m3
Distance along pond  500 m
Depth5m
SandconcentrationSFR
Yield stress = 200 kPa
Density fines = 1750 kg/m3
Density sand = 1660 kg/m3
sand discharge
Depth5m
sand discharge
Pond with soft tailings: inflowing sandy
slurry will mix with tailings pond
Pond with strong tailings: inflowing sandy
slurry will cap the tailings pond

26. Conclusions
- Developed a non-Newtonian Delft3D version, specifically
optimised for oil sand tailings
- But: many possibilities beyond the oil sands industry (fluid mud,
turbidity currents, water injection dredging, reservoir failure)
- We encourage sharing of beta releases of Delft3D slurry and are
open for cooperation!