Learn how to use CFD and FEA simulation together to optimize building designs before construction. This slide deck and webinar focus on using a combination of Natural Frequency Analysis and Vortex Shedding to determine design faults, and how to improve and optimize for quicker results. Want to learn more? Subscribe to our YouTube channel to learn everything you need to know about CFD, FEA, and Thermal Simulation: https://www.youtube.com/channel/UCIi21t-7PVPNECXeAS0z7pw

1. APPLICATIONS OF CFD & FEA
IN THE CONSTRUCTION INDUSTRY
JON WILDE

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8. BUILDING STRUCTURE – CFD AND MODAL FREQUENCY ANALYSIS
● Question 1
○ What are the modal
frequencies of the main
structure?
● Question 2
○ How does the flow move
around the building and
could the wind loads excite
the structure?
80m

9. WHAT IS A NATURAL FREQUENCY?
● Everything vibrates and has
resonant frequencies
● Some frequencies can cause
parts to ‘sing’. This is a natural
frequency
● A good example is a guitar string
○ Here we want vibration to
occur
● If we understand the vibration,
we can dampen it

10. WHAT IS NATURAL FREQUENCY?
● Everything vibrates and has
resonant frequencies
● Some frequencies can cause
parts to ‘sing’. This is a natural
frequency
● A good example is a guitar string
○ Here we want vibration to
occur
● If we understand the vibration,
we can dampen it
○ This dog seems to have it
handled

11. WHY DOES IT MATTER?
● Here is one example why we need to
know the natural frequencies of a
structure
○ They can be… nasty
(Source: https://giphy.com/gifs/cinemagraphs-bridge-tacoma-duatwzNErHFKw)

12. PART 1: MODAL FREQUENCY ANALYSIS

13. HOW TO GET STARTED
1. CAD IMPORT
Upload your CAD model
or import it from other cloud
services into SimScale.
2. SIMULATION SETUP
All steps to define and run
a simulation are done
within SimScale.
3
3. DESIGN DECISION
Use simulation insights
to make better and faster
design decisions.

14. SIMULATION SETUP – NATURAL FREQUENCY ANALYSIS
Load Bearing Structure of the Building
Floors
Columns
● Structural skeleton of the building consists of
○ 30 floors at 2.5m intervals
○ 8 columns across the entire length
○ 80m total height

15. SIMULATION SETUP – NATURAL FREQUENCY ANALYSIS
Fixed Support
Material
● Concrete: Entire structure
Boundary Conditions:
● Fixed Support: Bottom faces of the columns

17. RESULTS – NATURAL FREQUENCIES OF THE BUILDING
Mode Frequency
1 0.209739
2 0.218836
3 0.299477
4 0.65987
5 0.679429
6 0.906195
7 1.19709
8 1.22184
9 1.53931
10 1.73041

18. RESULTS – NATURAL FREQUENCIES OF THE BUILDING
Mode Frequency
1 0.209739
2 0.218836
3 0.299477
4 0.65987
5 0.679429
6 0.906195
7 1.19709
8 1.22184
9 1.53931
10 1.73041

19. RESULTS – NATURAL FREQUENCIES OF THE BUILDING
Eigenmode-1
0.209 Hz
Eigenmode-2
0.2188 Hz
Eigenmode-3
0.29944 Hz
Eigenmode-4
0.6598 Hz

20. PART 2: VORTEX SHEDDING ANALYSIS

21. SIMULATION SETUP – VORTEX SHEDDING ANALYSIS
● Inlet
○ Velocity inlet profile
(maximum velocity of
36.6m/s at 37m from
ground)
● Outlet
○ Pressure outlet
● Side walls
○ Slip (no friction)
Pressure Outlet
Velocity Profile

22. VORTEX FREQUENCY AT DIFFERENT WIND DIRECTIONS
3
Case 1
Wind in x direction
Case 2
Wind at 45 degrees Case 3
Wind at 90 degrees

23. WIND LOAD ANALYSIS
● SimScale will predict the vortex
shedding frequencies for each wind
direction
● Once extracted, we will compare
these frequencies with the modes
from the previous analysis

25. RESULTS – CFD Analysis
Force in Y direction
Oscillations due to vortex shedding

26. DIRECTION 1 – VORTEX SHEDDING

27. DIRECTION 2 – VORTEX SHEDDING

28. DIRECTION 3 – VORTEX SHEDDING

29. DIRECTION 1 – VORTEX SHEDDING

30. RESULTS – CASE I
Vortex shedding on a vertical plane

31. RESULTS – CFD vs FREQUENCY RESPONSE
Modal Frequencies (FEA)
Mode Frequency
1 0.209739
2 0.218836
3 0.299477
4 0.65987
5 0.679429
6 0.906195
7 1.19709
8 1.22184
9 1.53931
10 1.73041
11 1.76
12 2.2
13 2.3
14 2.35
15 2.9
CFD Analysis
Flow Direction Force Frequency
x 1.9
x 2.1
x 2.9
45 0.6
45 2
90 2.2
90 2.6
90 2.6

32. CONCLUSION
● There are two modal frequencies that
cross over with the transient wind
loads
○ Internal change
■ Damping
■ Re-design
○ External change
■ Modify building shape