The Boston Seaport District is completely exposed to the ocean, so it is common for wind speed to reach 15+ m/s (~34 mph). Further compounding the problem, wind speeds increase drastically in unobstructed sections of the cityscape, such as on main roads or in canals, due to the Venturi effect. The goal of this analysis is to understand the wind pattern near the Fort Point Channel, separating the two sections of the city and discuss the findings. Check out the official webinar page here: https://www.simscale.com/webinars-workshops/boston-seaport-wind-analysis/

1. PEDESTRIAN WIND COMFORT
SEAPORT DISTRICT, BOSTON
MATT BEMIS

2. MATT BEMIS
Application Engineer
4+ years of experience in CFD modeling of
electronics cooling, turbomachinery, external
aerodynamics, and automotive applications.
Before joining SimScale, he worked with
several other CFD solutions and did product
support and consulting.

3. 1. Benefits of Using Simulation
2. Introduction to SimScale
3. Today's Topic: Pedestrian Wind Comfort
4. Live Demonstration
5. Results Summary
6. Q & A

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11. PEDESTRIAN WIND COMFORT: SEAPORT BOSTON
OVERVIEW
Cities which neighbor bodies of water
can experience unusually high
pedestrian discomfort due to high winds
from the ocean & the Venturi effect.
Architects and building designers are
increasingly considering pedestrian
wind comfort during initial design
phases. Building location/orientation
can be optimized to minimize
discomfort.

12. THE VENTURI EFFECT
OVERVIEW
Velocity must increase as it passes
through a constriction. This effect is
named after Italian physicist Giovanni
Battista Venturi.
What does this mean for wind
engineering? Buildings and other
obstructions will force an increase in
wind speed through city streets and
other unobstructed channels.
(Source: https://i.stack.imgur.com/gTqm4.png )

13. PEDESTRIAN WIND COMFORT: SEAPORT BOSTON
OVERVIEW
Reports* show the different outcomes in
regards to pedestrian wind comfort :
● Shops untenanted
● Parks under utilized
● Personal injury
● Venturi effect in passages
● Wind-blocking
* http://www.urbanphysics.net/windcomfort.htm

14. THE BEAUFORT WIND FORCE SCALE
Strength (Bf) Description Wind speed at 1.75m above
ground (m/s)
Effects
0 - 1 Quiet, very light breeze 0 - 1 Quiet, no sensible wind.
2 Light breeze 2.4 - 3.8 The wind is felt on the face, leaves rustle.
3 Gentle breeze 3.9 - 5.5 The hair is shaken, leaves and twigs are in constant motion;
light flags extended.
4 Moderate breeze 5.6 - 7.5 Raises dust and loose paper; small branches moved.
5 Fresh breeze 7.6 - 9.7 Small trees in leaf begin to sway; crested wavelets form on
inland waters.
6 Strong breeze 9.8 - 12 Large branches in motion; whistling heard in telegraph wires;
umbrellas used with difficulty.
7 High wind,
moderate/near gale,
12.1 - 14.5 Whole trees in motion; inconvenience felt when walking
against the wind.
8 Gale,
fresh gale
14.6 - 17.1 Twigs break off trees; generally impedes progress.

15. BACKGROUND

16. LATTICE BOLTZMANN METHOD
Lattice Boltzmann Methods (LBM)
are meshless CFD algorithms which
use collision theories to predict the
fluid behavior.
Some advantages are:
● Less computational time
● Less computational power
● Simple and easy procedure
● Meshless (complex geometries)
● Transient phenomena

17. LATTICE BOLTZMANN METHOD

18. TEST CASE: SEAPORT BOSTON
OBJECTIVES
● Simulate how wind from the
harbor affects pedestrian comfort
● Detect windy areas in the
vicinities where pedestrians will
be active
● Become familiar with LBM in
SimScale and how the platform
can help determine pedestrian
wind comfort

19. TEST CASE: SEAPORT BOSTON
TEST CASE
● Twice a day, thousands of
pedestrians walk across Fort
Point Channel between Work &
South Station Terminal
● Does the Venturi Effect
increase wind speed and
discomfort on the Fort Point
Channel bridges?
● What is the wind profile of this
area?

20. THE CAD MODEL
A CAD model (SketchUp) of Seaport Boston was created

21. WIND VELOCITY
● Wind speed data obtained from
Logan Airport
● ~13% of the year, Boston is at a level
6 on Beaufort Scale
● Level 6 = 10.8 - 13.9 m/s
(Source: https://epw.s3.amazonaws.com/USA_MA_Boston-Logan.Intl.AP.725090_TMY3.pdf)

22. ATMOSPHERIC BOUNDARY LAYER
● Atmospheric boundary layer obtained
via spreadsheet calculations
● Aerodynamic roughness assumed to be
0.0002 (ocean)
● Weather data assumed to be collected
at 10 meters
● Height vs. Velocity table generated via
logarithmic law

23. SETUP: WIND DIRECTION
● Wind direction is WSW
● 22.5 degrees CCW of horizontal
● 14 m/s @ 10 meters, logarithmic
ABL as inlet boundary condition
● No-slip boundary condition on
ground
● Slip boundary condition on side,
top
● Pressure outlet at end of domain
● 200 seconds of transient analysis

24. SETUP: MESH REFINEMENT

25. SETUP: MESH REFINEMENT

27. SIMULATION RUN: TRANSIENT STATE
Highly unsteady, turbulent flow
Large velocity fluctuations

28. SIMULATION RUN: TRANSIENT STATE
Turbulent flow leads to changing
direction
Venturi effect in streets

29. SIMULATION RUN: TRANSIENT STATE
Transient boundary
layer flow over buildings
observed

30. SIMULATION RUN: TRANSIENT STATE