Urban Center (Niigata)
**********************

.. html metadata
.. meta::
   :description: Urban Center (Niigata)
   :keywords: Digital Wind Tunnel, Validation, Urban Center

.. Public Project
.. ==============
.. .. link to insight page
.. `AeroSim Web App`_

.. .. _AeroSim Web App: https://insight.aerosim.io/cp/TODEFINE/


.. animations, surfaces and contours
.. figure_expand:: /_static/niigata/visuals_1.png
   :alt: Urban Center
   :figwidth: 100%
   :align: center

1. Project Description
======================

The current study is a reproduces Niigata pedestrian comfort assessment available in `Guidebook for CFD Predictions of Urban Wind Environment <Guidebook_for_CFD_Predictions_of_Urban_Wind_Environment_>`_ from Architectural Institute of Japan wth AeroSim's CFD solver.

.. _Guidebook_for_CFD_Predictions_of_Urban_Wind_Environment: https://www.aij.or.jp/%20jpn/publish/cfdguide/index_e.htm
.. Cite experimental database or paper

The case consists of building complexes with simple building shape in actual urban area, the probes are distributed as shown below:

.. Probes location and wind direction orientation
.. figure_expand:: /_static/niigata/probes.svg
   :alt: Probes Layout
   :max-width: 640px
   :align: center

The velocities were measured at an equivalent height :math:`H=15.9m`. The wind directions chosen to be simulated were:

.. list of analyzed cases
.. csv-table:: Wind Directions
   :file: /_static/niigata/cases.csv
   :widths: 20, 20, 20, 20, 20
   :header-rows: 0


2. Simulation Setup
===================

The Synthetic Eddy Method (SEM) boundary condition is applied at the inlet of the computational domain.
Solid fins are distributed across the floor to ensure the desired velocity and turbulence profiles during flow development length.
A Neumann boundary condition is applied at the remaining boundaries.

The rotative table with equivalent diameter :math:`D=420m` was centered :math:`128H` from inlet, and 5 grid refinement levels (:math:`lvl\,0` to :math:`lvl\,4`) were adopted:

.. Top and lateral views, indicating the box and body refinements
.. figure_expand:: /_static/niigata/grid.svg
   :alt: Computational Grid
   :figwidth: 100%
   :align: center

A 1:2 refinement ratio is estabilished between levels, and the simulation parameters at grid :math:`lvl\,4` were:

.. constant simulation parameters
.. csv-table:: Dimensionless Parameters
   :file: /_static/niigata/params.csv
   :widths: 80, 20
   :header-rows: 0

The equivalent parameters in full scale are:

.. full scale parameters
.. csv-table:: Full-scale Parameters
   :file: /_static/niigata/full_scale.csv
   :widths: 80, 20
   :header-rows: 0

The computational resources required were:

.. hardware and execution aspects
.. csv-table:: Computational Resources
   :file: /_static/niigata/perf.csv
   :widths: 30, 18, 18, 18, 18
   :header-rows: 0

3. Inflow
=========

An empty domain simulation is performed to measure the incident velocity and turbulence profiles.
A probe line is placed at the position where the building will be located.
The average velocities used for calculating the pressure coefficient and convective time scale are taken from this simulation.

Wind Profiles
-------------

.. profiles of velocity, turbulence and integral lenght scale
.. figure_expand:: /_static/niigata/inflow/inflow_profile.svg
      :alt: Inflow Profile
      :max-width: 640px
      :align: center


Wind Spectra
------------
The power spectral density of the velocity components at height :math:`H` are compared with theoretical Von Kármán curves to validate the atmospheric flow.

.. spectra of velocity components
.. figure_expand:: /_static/niigata/inflow/spectrum.svg
      :alt: Inflow Spectrum
      :figwidth: 100%
      :align: center


4. Results: Average Velocities
==============================

Probes Statistics
-----------------

The average velocity at each probe position is shown below against experimental data.

.. figure_expand:: /_static/niigata/rel_vel_by_probe_E.svg
  :alt: Velocities E
  :figwidth: 100%
  :align: center

.. figure_expand:: /_static/niigata/rel_vel_by_probe_W.svg
  :alt: Velocities W
  :figwidth: 100%
  :align: center

.. figure_expand:: /_static/niigata/rel_vel_by_probe_N.svg
  :alt: Velocities N
  :figwidth: 100%
  :align: center

.. figure_expand:: /_static/niigata/rel_vel_by_probe_S.svg
  :alt: Velocities S
  :figwidth: 100%
  :align: center


Velocity Profile
-----------------

**E:**

.. figure_expand:: /_static/niigata/colormap_E.png
  :alt: Velocities E
  :figwidth: 100%
  :align: center

**W:**

.. figure_expand:: /_static/niigata/colormap_W.png
  :alt: Velocities W
  :figwidth: 100%
  :align: center

**N:**

.. figure_expand:: /_static/niigata/colormap_N.png
  :alt: Velocities N
  :figwidth: 100%
  :align: center

**S:**

.. figure_expand:: /_static/niigata/colormap_S.png
  :alt: Velocities S
  :figwidth: 100%
  :align: center

Execution Notes
===============

.. csv-table:: Execution Notes
   :file: /_static/niigata/exec.csv
   :widths: 50, 50
   :header-rows: 0

Changelog
=========

* **19 Jan 2025**: Added scattering plots