AirSketcher Manual

Welcome to the AirSketcher user manual. This guide will walk you through every essential and advanced feature of the software for setting up and running CFD simulations with ease.

Introduction

AirSketcher is a lightweight 2D CFD simulation and visualization tool built for rapid design exploration and intuitive analysis. Unlike traditional CFD platforms that require extensive setup, meshing, and scripting, Air Sketcher simplifies the process β€” just draw your domain, press run, and see results.

Designed for speed and usability, it enables engineers, designers, educators, and students to test airflow concepts on the fly β€” whether across mechanical structures, ventilation layouts, or environmental enclosures.

With built-in modules, Air Sketcher delivers:

No CAD. No complex setup. No barriers. Just insight β€” fast.

Installation

To install AirSketcher, follow these simple steps:

  1. Download the installer

Locate and run the provided setup.exe file.

  1. Activate with your license key

During the first launch, you’ll be prompted to enter the license key you received after purchase.

  1. One-time online verification

The software will briefly connect to the server to verify your license. If the key is valid, a local license file will be generated and saved on your machine.

  1. Offline usage enabled

After activation, AirSketcher will no longer require an internet connection. You can run it offline anytime.

πŸ’‘ *Make sure to keep your license key in a safe place for future reference

System Requirements

To ensure smooth operation, AirSketcher requires the following minimum system specifications:

πŸ–₯️ Operating System

βš™οΈ Hardware

🌐 Internet

βœ… AirSketcher is optimized for lightweight 2D simulations and user-friendly visualization. It does not require a high-end workstation.

Quick Start Guide

Follow these steps to run your first CFD simulation in AirSketcher:

Launch the Application

Double-click AirSketcher.exe. The main interface will open with a clean canvas and controls on the left.

Set the Wind Speed

Define Your Simulation

Domain

Expert Options

Click Expert Options β–Ά to access advanced controls like:

Run the Simulation

View Results

Once the simulation is complete, explore the results using the top results panel:

Each result opens in a new window with zoom, colorbars, tooltips, and export options.

Save Case and Data

Export your processed simulation as a .pkl file using the Save button if needed for post-processing or external tools.

βœ… You’re now ready to explore more advanced configurations!

User Interface Overview

When you launch AirSketcher, you’ll see the interface divided into key functional areas:

The main graphic user interface (GUI)

Left Panel β€” Simulation Controls

This is where you control how the simulation runs:

Live Progress View

The preview includes:

It also calculates a Design Score using the following formula:

\[ \text{Design Score} = \frac{100 \cdot \overline{V}_{\text{ROI}}}{1 + 0.5 \cdot \sigma^2_{\text{ROI}}} \] where:

The Design Score rewards airflow that is both strong and consistent within the target region. Higher scores indicate faster average velocity with lower variation β€” ideal for achieving stable, efficient ventilation performance.

This is based on the Courant–Friedrichs–Lewy (CFL) condition, which limits the time step for stability:

\[ \Delta t \leq \frac{Ly}{u} \] Where:

If the flow is slow and the grid is very fine, the required time step \(\Delta t\) becomes extremely small. If the simulation does not reduce the time step accordingly, it may become unstable or diverge.

To prevent this, Refine Flow automatically activates when Ly is smaller than a safe threshold for the current velocity.

Users may still turn Refine Flow ON or OFF manually. However, if it is turned ON automatically, the system will not disable it without user input.

Right Panel β€” Sketch and Image Tools

Sketch & Tools

From top to bottom:

Image Tools

Bottom Three Icons:

Center Canvas β€” Drawing & Simulation View

This is your main workspace:

Bottom β€” Residuals and Log Console

Simulation Setup

Setting up your simulation involves defining the environment where air will flow. This includes specifying the domain size, placing obstacles, and applying boundary conditions. AirSketcher offers an intuitive interface to guide you through each step.

Setting Domain Size

To define the vertical size of your simulation area:

  1. Click on β€œSet Domain Height (Y)” in the Expert Options panel.
  2. Enter your desired height value in meters.
  3. The domain length (X) is automatically scaled based on the canvas width.

πŸ’‘ Tip: Ensure all obstacles are placed within the domain and away from boundaries to minimize their impact on flow and avoid simulation errors.

Defining Obstacles

Obstacles represent solid objects like buildings, walls, or terrain features that influence airflow.

πŸ“ Note: Ensure obstacles form closed loops to be treated as solids.

Expert Options

These expert settings give you deeper control over simulation physics and performance. To reveal them, click the Expert Options β–Ά button under the Wind Speed setting.

Expert mode menu

Gravity Enabled

Applies downward gravity to the airflow. Useful for buoyancy-driven flows (e.g., warm air rising) or terrain-influenced drafts. When disabled, the simulation assumes horizontal-only flow without vertical buoyancy effects.

Wind Tunnel Mode

This mode applies slip-wall boundary conditions to the top and bottom walls of the simulation domain, simulating a frictionless tunnel.

Slip Wall means:

Use this for testing designs in wind tunnel-like conditions or when vertical wall interference should be minimal.

Slip Wall (Top)
β”Œβ”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”
β”‚                            β”‚
β”‚  β†’ β†’ β†’ β†’ β†’ β†’ β†’ β†’ β†’ β†’ β†’     β”‚
β”‚  β†’ β†’ β†’ β†’ β†’ β†’ β†’ β†’ β†’ β†’ β†’     β”‚    Flow direction β†’
β”‚  β†’ β†’ β†’ β†’ β†’ β†’ β†’ β†’ β†’ β†’ β†’     β”‚
β”‚                            β”‚
β””β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”˜
Slip Wall (Bottom)

Symmetry Boundary means:

If Wind Tunnel Mode is Off: Symmetry Boundary, top and bottom boundaries apply symmetry conditions instead. - Perpendicular velocity is zero
- No variation across the boundary (zero gradient of velocity and pressure)

This is ideal for simulating mirrored or duplicated domains.

Symmetry Boundary
────────────────────────────────
      ↓↓↓↓↓↓↓↓↓↓↓↓↓↓↓↓
     Flow mirrored here
      ↑↑↑↑↑↑↑↑↑↑↑↑↑↑↑↑
────────────────────────────────

Ground Friction

When enabled, the bottom wall becomes no-slip, simulating ground drag. That means velocity at the bottom = 0, mimicking real-world friction from ground or terrain.

Top boundary remains a slip wall.

Slip Wall (Top)
β”Œβ”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”
β”‚                    β”‚
β”‚  β†’ β†’ β†’ β†’ β†’ β†’ β†’ β†’   β”‚
β”‚   β†’ β†’ β†’ β†’ β†’ β†’ β†’    β”‚
β”‚    β†’ β†’ β†’ β†’ β†’       β”‚
β”‚     β†’ β†’ β†’          β”‚
β”‚       β†’            β”‚
β”‚         U = 0      β”‚  ← No-slip Ground (velocity = 0)
β””β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”˜

ABL Inlet

The Atmospheric Boundary Layer (ABL) inlet applies a vertical velocity profile that grows with height, mimicking outdoor wind over terrain and buildings.

Velocity Profile Formula

The wind speed follows a power law:
\(u(y) = U_{\text{ref}}\left(\dfrac{y}{H}\right)^{\alpha}\)

Where - \(u(y)\): velocity at height \(y\)
- \(U_{\text{ref}}\): reference velocity at height \(H\)
- \(H\): reference height (often the inlet top)
- \(\alpha\): shear exponent (controls profile steepness)

ABL Profile (ASCII-safe for Zettlr)

U(y)
|               o  <- U_ref
|               o
|              o
|             o
|           o
|          o
|        o
|      o
|   o
+-------------------------------------- y
0                                      H

Higher \(\alpha\) values produce stronger shear near the ground (steeper gradient at small \(y\)).

Typical \(\alpha\) by Terrain

Terrain type \(\alpha\) range
Open land / water 0.14–0.16
Suburban areas 0.22–0.27
Urban / dense forest 0.30–0.40

When to Use an ABL Inlet

Notes

AMR Enabled

AMR (Adaptive Mesh Refinement) rebuilds the grid so it is fine where accuracy matters and coarser elsewhereβ€”boosting speed without sacrificing fidelity.

How it works - ROI-driven refinement: A Region of Interest (ROI) is detected around geometry/flow features (obstacles, porous polygons, blower zones are treated as fluid so the ROI grows around them). - Fine inside, coarse outside: Inside the ROI we keep every row/column; outside, four log-spaced strips (bottom/top/left/right) place cells dense near the ROI and stretched toward the domain edges using a smooth exponential spacing. - Edges preserved: The first/last rows and columns of the full domain are always included. - Auto coarsening guard: A coarsening β€œfactor” is auto-selected from a small set so at least ~5% of cells remain outside the ROI in both directions. If none fits, AMR is disabled with a warning.

What gets remapped - Fields: u, v, p, b, nu_tilda - Materials/forcing: obstacles, porosity_grid, blower_grid_x, blower_grid_y - Grid: X, Y rebuilt from the selected indices
- One-time snapshot of the full-resolution state is saved on first AMR run for revert/post-processing: *_original, X_original, Y_original, sizes and spacings, and roi_original. - The exact index sets used are exported as globals:
i_indices_combined, j_indices_combined.

When it runs / skips - Controlled by the UI checkbox.
- Skips if: AMR disabled, no ROI found, no suitable factor, or memory error.

Stability tips (pseudo-transient) - AMR increases local effective CFL away from the ROI. If using aggressive time stepping, clamp with: - Soft convective cap (tighter when amr_applied is True), and/or - Convective cap based on dx, dy and local max velocities. - These small guards typically prevent β€œstable w/o AMR but diverges with AMR”.

After enabling - Updates nx, ny, X, Y to the adaptive grid, - Refreshes the view (AMR grid + streamline preview), - Sets amr_applied = True.

Note: AMR is not turned off by porous/blower zones; instead they are included in the ROI so refinement captures their effects.

Scale Input Wind Speed

This tool adjusts the wind speed to maintain Reynolds number similarity when working with scale models.

Reynolds number (\(Re\)) is approximated by:

\[ Re = \frac{\rho \cdot U \cdot L}{\mu} \] where:

When Should You Use This?

You only need to use Scale Input Wind Speed if your simulation is based on a scaled-down physical model (not full size).

For example, if you’re simulating airflow around a miniature car in a wind tunnel, this function adjusts the inlet speed so that the flow behaves the same as it would around the real, full-size car.

This is crucial because airflow patterns depend on the Reynolds number. A small object at full wind speed will experience different flow behavior (e.g., laminar vs turbulent) than a full-size object.

When You Don’t Need It

If your geometry is modeled at true 1:1 scale (real-world size), then you don’t need to use this feature. Just enter the actual wind speed directly.

Using it in a 1:1 simulation could distort physical accuracy.

Summary

Set Domain Height

Changes the vertical height (Ly) of the simulation domain.

You can either:
- Enter the new height manually (minimum = 1.0 meters)
- Draw a vertical reference line and input the real-world height

The horizontal width (lx) updates automatically using:

lx = 2 * ly

After applying changes, the simulation reloads with the new dimensions. Save your work before using this feature.

Porous and Blower Zones

This feature allows you to define polygon regions that either resist airflow (porous or vegetation zones) or inject airflow (blower zones). These zones are fully integrated into the momentum solver.

Porous Zones β€” Flow Resistance

Porous zones are used to simulate vegetation, fences, or other semi-obstructive elements that reduce wind velocity.

Two ways to define resistance:

LAI to Porosity Mapping

When LAI is used, porosity is computed from an exponential decay model:

\[ \text{Porosity} = 100\, e^{-0.5\,\text{LAI}} \]

This captures how denser vegetation obstructs airflow more effectively.

LAI Porosity (%) Vegetation Type
0 100% No vegetation
1 ~60% Light foliage
3 ~22% Moderate vegetation
5 ~8% Dense canopy
7 ~3% Very dense vegetation

How the solver actually uses LAI

Plan (Top) View - Use species LAI directly (e.g., Apple 2–4, Banana 3–6).
- No height input is needed; the model is per-unit depth out of plane.

Side (Section) View - Enter the same LAI; do not calculate height by hand.
- The solver infers \(H_c\) from your drawn polygon’s vertical thickness and computes \(\text{LAD}=\text{LAI}/H_c\) per cell.

Notes - Published LAI values are already integrated over canopy height in field measurements.
- Longer polygons (x-direction) don’t change LAI interpretation; they just extend where the drag is applied.

Flow Damping Equation

Porous zones introduce resistance in the velocity update step based on porosity:

Drag Coefficient:

\[ C_d = \frac{(1 - \phi)^2}{\phi^3 + \varepsilon} \]

Where:

Velocity Damping Applied in Solver:

\[ u = u_{\text{adv}} - \Delta t \cdot C_d \cdot u_{\text{adv}} \\ v = v_{\text{adv}} - \Delta t \cdot C_d \cdot v_{\text{adv}} \]

This reduces the wind velocity inside porous zones during each time step.

Tree Species β€” Typical LAI Ranges

Use these values as guidance when modeling real-world vegetation:

🌳 Sample Tree LAI Values (Typical Ranges)

β€’ Acacia (Acacia spp.)……………… 3.5–6.0
β€’ Apple (Malus domestica)…………… 2.0–4.0
β€’ Areca Palm (Dypsis lutescens)……… 1.5–2.5
β€’ Avocado (Persea americana)………… 2.5–4.5
β€’ Bald Cypress (Taxodium distichum)….. 3.0–5.0
β€’ Banana (Musa spp.)………………… 3.0–6.0
β€’ Bamboo (various species)………….. 2.0–5.0
β€’ Beech (Fagus grandifolia)…………. 2.5–4.0
β€’ Birch (Betula spp.)……………….. 2.0–4.0
β€’ Camphor Tree (Cinnamomum camphora)…. 2.5–4.5
β€’ Casuarina (Casuarina equisetifolia)… 3.0–4.0
β€’ Cherry Blossom (Prunus serrulata)….. 3.0–4.5
β€’ Chinese Elm (Ulmus parvifolia)…….. 2.5–4.0
β€’ Coconut Palm (Cocos nucifera)……… 1.5–2.5
β€’ Coffee (Coffea arabica)…………… 1.5–3.0
β€’ Douglas Fir (Pseudotsuga menziesii)… 2.0–4.0
β€’ Eucalyptus (Eucalyptus spp.)………. 2.0–4.0
β€’ Fig (Ficus carica)………………… 2.0–3.5
β€’ Ginkgo (Ginkgo biloba)……………. 1.5–2.5
β€’ Guava (Psidium guajava)…………… 2.5–4.0
β€’ Jackfruit (Artocarpus heterophyllus).. 3.0–5.5
β€’ Japanese Maple (Acer palmatum)…….. 2.0–3.5
β€’ Lemon (Citrus limon)………………. 2.0–3.5
β€’ Litchi (Litchi chinensis)…………. 3.0–5.0
β€’ Live Oak (Quercus virginiana)……… 3.0–5.0
β€’ Mahogany (Swietenia spp.)…………. 2.5–4.5
β€’ Mango (Mangifera indica)………….. 3.0–5.0
β€’ Neem (Azadirachta indica)…………. 2.0–3.5
β€’ Olive (Olea europaea)…………….. 1.5–3.0
β€’ Papaya (Carica papaya)……………. 2.0–4.0
β€’ Pine (Pinus spp.)…………………. 2.0–5.0
β€’ Rain Tree (Albizia saman)…………. 4.0–7.0
β€’ Red Cedar (Juniperus virginiana)…… 2.0–3.5
β€’ Red Maple (Acer rubrum)…………… 2.5–4.5
β€’ Rubber Tree (Hevea brasiliensis)…… 2.5–4.5
β€’ Sugar Maple (Acer saccharum)………. 3.0–5.0
β€’ Sycamore (Platanus occidentalis)…… 3.5–6.0
β€’ Tamarind (Tamarindus indica)………. 3.0–5.0
β€’ Teak (Tectona grandis)……………. 2.5–4.5
β€’ Tulip Tree (Liriodendron tulipifera).. 3.5–5.5
β€’ Walnut (Juglans regia)……………. 3.0–4.5
β€’ White Oak (Quercus alba)………….. 2.5–4.5

Blower Zones β€” Air Injection

Blower zones are polygonal areas that inject momentum into the flow field, simulating fans or ducts.

Each blower has:

Injected Velocity Components:

\[ u = V \cdot \cos(\theta), \quad v = V \cdot \sin(\theta) \]

Where:

The computed velocity is applied to grid cells in the blower zone. Neighboring cells receive a transition blend to prevent sharp discontinuities.

Volume Balance Aid

To ensure airflow consistency, the system automatically computes how much velocity is required at the inlet to match the total blower outflow:

\[ V_{\text{inlet}} = \frac{3 \cdot Q_{\text{total}}}{A_{\text{inlet}}} \]

Where:

This recommendation appears (in the log console) as a suggestion for the minimum inlet velocity.

Image Processor and Wind Locator

This tool helps you quickly prepare images for CFD simulation and align them with real-world wind conditions β€” ideal for architects, urban planners, and HVAC designers working with satellite imagery, blueprints, or scanned floorplans.

The GUI of Image Processor and Wind Locator
Prevailing wind direction control wheel

Image Setup and Wind Alignment

Users can load any image of interest β€” from a simple floorplan to an airfoil β€” into the simulation domain.

If needed, the system provides edge detection tools to help extract clear outlines from the image β€” especially useful when loading floorplans or sketches from the Internet.

Two sliders at the top of the interface control the edge detection threshold, allowing you to fine-tune what is considered an edge based on contrast. This ensures cleaner geometry recognition before simulation.

To simulate realistic wind exposure:

The tool offers two independent workflows:

a. Preparing and Exporting an Image

Open the Image Processor

The icon of image processor and wind locator

Load Your Image

Refine Image Outlines

Use the two sliders to control how clearly shapes and boundaries are extracted from your image.

The image preview updates in real time over a clean white background, giving you immediate feedback.

Export for Simulation

b. Adding Real Wind Data

Enter Coordinates

Latitude / Longitude Input

What Happens Behind the Scenes

Visual Map Overlay

Align with Wind

Reading a Wind Rose

A wind rose is a visual summary of how wind speed and direction are distributed at a specific location.

Below is an example from DUNEDIN AERODROME AWS, approximately 41.95 km from the reference point.

Wind Rose

How to Read the Wind Rose:

Setting Wind Inputs in a Simulation

Wind Direction

πŸ’‘ Simulation Logic:
In the simulation environment, the wind always enters from the left side of the domain. This is because the software sets the inlet boundary on the left, with flow moving horizontally rightward.

What You Need to Do:
If wind in reality comes from NE (45Β°):

Example:

If real wind is from SW (225Β°):

πŸ“Œ Always align wind direction relative to the left-side inlet, since that’s where airflow begins.

Wind Speed
Example Setup:
Wind direction: 45Β° (from NE) or 225Β° (from SW)
Wind speed (at a reference height 10m): 6 m/s

ℹ️ If using ABL (Atmospheric Boundary Layer), the 5 m/s typically applies at the domain top (e.g., 10 m or 100 m height).

Summary

Element Value (from rose)
Dominant Wind From NE and SW
Frequency Peak ~17.5% from SW
Typical Speed 4–8 m/s
Suggested Inlet 6 m/s from SW (225Β°)

When You’re Ready

  • Return to the main simulation screen
  • Use the Import image icon (right panel) to import your .pkl obstacle layout
  • Click Run to begin simulation

Running a Simulation

Once your geometry, wind zones, and simulation parameters are set, running a simulation in AirSketcher is straightforward β€” though behind the scenes, the solver performs several intelligent steps to ensure stability, accuracy, and physical realism.

How to Start

  1. Click the β–Ά Run Simulation button.
  2. The solver begins processing your setup: geometry, wind, zones, and any porous or blower definitions.
  3. A live residual plot opens to monitor convergence.

What Happens During the Simulation

For each iteration, the solver performs:

Residual_u = |u - u_prev|
 Residual_v = |v - v_prev|
 Residual_p = |p - p_prev|

These residuals are shown live in the solver graph.

Live Monitoring

Every 200 iterations (default, configurable):

When the Simulation Stops

The solver now uses explicit, code-level criteria for stopping or notifying you:

Other Insights

After Completion

Notes

Solver behavior depends on: - Domain height (ly) - Inlet speed - CFL condition (automatically adjusted if Refine Flow is on)

πŸ’‘ Pro Tip

Not sure if the simulation is stable?

Look at the residual plot:

Visualizing Results

After the simulation is complete, you can view the results using the panel of visualization tools. Each button provides a specific type of analysis to help interpret flow behavior, pressure distribution, or derived performance.

Velocity Contour

The Velocity Contour tool renders a filled color map of the fluid velocity magnitude across your simulation domain. It helps you spot high-speed regions, wake formations, and flow symmetry β€” all at a glance.

Velocity Contour

Features

Usage Tips

πŸ“Œ Notes

Pressure Contours

The Static Pressure visualization presents how pressure is distributed throughout the domain, particularly highlighting high and low zones around obstacles.

Pressure contour

Key Features

Aerodynamic Analysis

⚠️ Important for Accuracy - Enable Refine Flow (adequate resolution near boundaries). - Run until mass-flow balance \(\ge 99\%\). - Poor convergence (e.g., \(<95\%\)) can yield unreliable lift/drag.

Aerodynamic Coefficients

Let \(q_\infty=\tfrac12\rho U_\infty^2\). We report both normalizations:

Where: \(F_x, F_y\) are pressure forces per unit span; \(\rho\) is air density (default \(1.225\ \mathrm{kg/m^3}\));
\(U_\infty\) is freestream speed; \(H\) is projected height; \(c\) is chord/streamwise extent.

Why two sets?
Different communities use different 2D references: [H] for bluff bodies; [c] for airfoils.
Both use the same \(\mathbf F\) and \(q_\infty\); only the length scale differs.

Details of Aerodynamics Analysis

Particle Tracking & β€œSmoke” Overlay

The Particle Tracking view animates tracer dots that follow your velocity field.
The optional Smoke overlay is a unitless, normalized density map built from recent particle paths. The tooltip shows a percent intensity.

Particle tracking & smoke overlay

Particle Tracking

Controls: Particle Speed, Color (dot brightness), Amount, plus Run/Reset, Stop, Exclude Region, Clear Exclusions, Set/Reset Particle Inlet, Show/Hide Porous Zones.

When Smoke overlay is on, particle dots are hidden to keep the image clear.

Smoke Overlay (normalized, unitless)

The overlay is advanced each frame on the plot grid from particle footprints.

Symbols

Per-frame pipeline

1) Bilinear deposit from dots \[ D \ \leftarrow\ \text{scatter of particle footprints (bilinear weights) in fluid }(M=1). \]

2) Compact Gaussian blur (thickness) \[ \tilde D \;=\; G_y(\sigma)\,*\,G_x(\sigma)\,*\,D. \]

3) Trail memory + add \[ C^{(k+1)} \;=\; \alpha\,C^{(k)} \;+\; \tilde D. \]

4) Outlet sponge A light attenuation near the right boundary reduces \(C\) to avoid build-up.

5) Mask solids \[ C^{(k+1)} \leftarrow M\odot C^{(k+1)}. \]

Display mapping (visualization only)

Keep contrast stable with a percentile EMA, then apply a gamma: \[ V_{\max}^{(k)}=(1-\beta)\,V_{\max}^{(k-1)}+\beta\,\mathrm{perc}_{98}\!\big(C^{(k+1)}\big), \] \[ I \;=\; \left[\min\!\left(1,\ \frac{C^{(k+1)}}{V_{\max}^{(k)}+\varepsilon}\right)\right]^{\gamma}. \] \(I\in[0,1]\) is what you see as β€œsmoke.” The tooltip reports \(100\,I\ \%\).

Reading values

What influences the overlay \(C\)

Accuracy & scope

Performance tips

Why is the tooltip a %?
The overlay normalizes \(C\) by a running high percentile to keep contrast stable, then displays \(I\) with a gamma. That makes values comparable frame-to-frame and avoids saturation. The tooltip simply reports \(100\,I\%\); there are no physical units.

Line Probe

The Line Probe tool extracts precise values across any two points in your flow domain.

Drawing a Line Probe
Line Probe Output

Steps

  1. Start Probe Click Line Probe β†’ draw a polyline along the path you want to sample.

  2. Reference Scaling (distance calibration)

    • If your domain axes are already 1:1 in meters, just press OK in the dialog (no calibration needed).
    • If your domain is scaled (pixels/CAD/image), draw a short reference line over a feature with a known real-world length, then enter that length (in meters). This sets the meters-per-unit scale so distances, mass flow rate, and integrals (e.g., int(U ds), int(U^2 ds), int(U^3 ds)) are computed correctly.

  3. Auto Plots

    • Velocity Magnitude vs Distance
    • Static Pressure vs Distance
    • Vx, Vy Components vs Distance

(β€œDistance” is shown in meters using the scale from Step 2.)

\(\dot{m} = \rho \cdot V_n \cdot A\)

  1. Interactive Table
    Shows sampled data: X, Y, V, P, Vx, Vy, \(\dot{m}\)

  2. Save
    Export composite PNG plot.

Graph (line probe) Description

This section explains what each line-probe graph shows and how the summary numbers are computed.
You draw a polyline; we resample the field along its arc-length \(s \in [0,L]\) with local segment lengths \(\Delta s_i\).
Velocity components are \(u_x, u_y\); the speed (velocity magnitude) is \(U = \sqrt{u_x^2 + u_y^2}\).

Raw vs smoothed curves. Each plot can show raw samples (markers) and a gently smoothed curve (solid line).
Integrals labeled β€œraw” are taken from the unsmoothed samples; those labeled β€œsmoothed” are taken from the displayed curve.
The data table always exports the raw samples.

Velocity Magnitude \(U\) [m/s]

Example: Using a near-surface line probe and \(\int U^3\,ds\) for sand transport

Goal. Estimate along-line aeolian sand transport over 2-D topography using Bagnold’s cubic law and the line-probe metric \(\int U^3\,ds\).

1) Bagnold scaling (form used here).
\[ q \;=\; C\,\frac{\rho}{g}\,\sqrt{\frac{d}{D}}\;u_*^{3} \] - \(q\): sand mass flux per unit width (kg·s⁻¹·m⁻¹)
- \(\rho\): air density, \(g\): gravity
- \(d\): grain size, \(D\): reference size
- \(u_*\): friction (shear) velocity
- \(C\): empirical constant Coefficient \(C\) (how to choose)
A commonly cited range is: \(C \approx 1.5\) (uniform, well-sorted sand) up to \(C \approx 2.8\) (widely graded sand)

Practical tip: start with \(C = 2.0\) and calibrate against any measured fluxes if available.

2) Link \(u_*\) to measured wind speed \(U\) at a fixed near-surface height.
Assume a log law at uniform \(z_{\text{ref}}\) and roughness \(z_0\): \[ U(z_{\text{ref}})=\frac{u_*}{\kappa}\,\ln\!\Big(\frac{z_{\text{ref}}}{z_0}\Big), \qquad u_*=\frac{\kappa\,U(z_{\text{ref}})}{\ln\!\Big(\frac{z_{\text{ref}}}{z_0}\Big)}, \] with \(\kappa\simeq0.40\).

3) Combine 1) and 2).
\[ q \;=\; K\,U^{3}, \qquad K \;=\; C\,\frac{\rho}{g}\,\sqrt{\frac{d}{D}}\, \left[\frac{\kappa}{\ln\!\Big(\frac{z_{\text{ref}}}{z_0}\Big)}\right]^3 . \] If \(z_{\text{ref}}\) and \(z_0\) are uniform along the probe, \(K\) is constant.

4) Draw a polyline line probe along the near-surface path.
Let vertices be \(\{(x_i,y_i)\}\) with arc-length spacings \(\Delta s_i\).
The tool’s metric is \[ \int_{\text{polyline}} U^{3}(s)\,ds \;\approx\; \sum_i U_i^{3}\,\Delta s_i . \]

5) Convert the metric to transport.
Total along-line flux (per unit span out of plane): \[ Q_{\text{line}} \;\approx\; K \int U^{3}\,ds . \] With SI inputs in \(K\), \(Q_{\text{line}}\) is in kg·s⁻¹.

6) Optional threshold for motion.
If a threshold friction velocity \(u_{*t}\) applies, set segments with \(u_*\le u_{*t}\) to zero. Using the log-law link, define \[ U_t=\frac{u_{*t}}{\kappa}\,\ln\!\Big(\frac{z_{\text{ref}}}{z_0}\Big), \qquad Q_{\text{line}} \;\approx\; K \sum_i \max\!\big(U_i^{3}-U_t^{3},\,0\big)\,\Delta s_i . \]

Assumptions / tips - Use one \(z_{\text{ref}}\) along the polyline (above the roughness sublayer).
- If \(z_0\) varies strongly, treat \(K\) locally as \(K_i\).
- Choose \(d\) and \(C\) for the expected sand (dry, non-cohesive).
- Your \(\int U^3 ds\) metric is a proxy for the Bagnold driver: larger values indicate stronger transport potential along the drawn path.

Static Pressure \(p\) [Pa]
Velocity Components \(u_x, u_y\) [m/s]
Mass Flow Across the Polyline [kg/s]

Let \(\rho\) be density and \(\mathbf{n}(s)\) the unit normal of the polyline (pointing to the measured side).
The normal velocity is \(V_n(s) = u_x(s)\,n_x(s) + u_y(s)\,n_y(s)\).

Units sanity check

Report

The Report tool builds a polished PDF and a Word-friendly bundle from your current simulation. It uses an ROI (rectangular Region of Interest) plus user-picked POIs (Points of Interest) to drive stats, charts, and AI-assisted narrative.

πŸ› οΈ Workflow

  1. Run a simulation
    Ensure velocity/pressure fields are available.

  2. Open AI Analysis
    Click Report / AI Analysis. A new window opens showing the velocity map.

  3. Draw the ROI

    • Drag a rectangle over the area you want analyzed.
    • Click Confirm ROI.

  4. Pick POIs (points to sample)

    • Click on the plot to drop one or more POIs (they’re numbered).
    • Use Delete Last POI or Reset All POIs if needed.
    • Click Confirm Points of Interest.

  5. Name the POIs

    • A Name Zones window appears listing β€œPoint 1”, β€œPoint 2”, …
    • Rename them (e.g., Inlet Corner, Mixing Chamber, Outlet).
    • Click Submit.

  6. Save the PDF
    You’ll be prompted for a PDF filename. After saving, a bundle folder and an AI pack (.json) are created beside the PDF, and the folder is opened for you.

πŸ“‹ What the Report Includes

πŸ“¦ Outputs

Notes & Tips

Qi-Flow

Qi-Flow (QFI) blends CFD with Feng Shui to assess air harmony, clarity, and comfort.

Visualization of Qi Flow Index

How QFI Works

Formulas:

Room Classification

Room Type Velocity Range QFI Score Color Use
Sha Chi \(|V| > V_{\text{opt}} + \sigma\) β€” Red Too fast, aggressive flow
Stagnant Zone \(|V| < V_{\text{opt}} - \sigma\) < 0.55 Gray Too slow or blocked
Calm Room 0.6–1.8 m/s > 0.80 Blue Sleep, study
Active Room 0.8–2.1 m/s 0.60–0.80 Green Balanced, energized
QFI Map Example

Tips for Qi-Aligned Flow

Troubleshooting & FAQ

(To be filled)

πŸ‘₯ Credits

Core Development

πŸ”– Licensing & Acknowledgements

AirSketcher may incorporate open-source components under compatible licenses.
All third-party libraries retain their original licensing terms.

If you redistribute or build upon this software, proper attribution is appreciated.

πŸ“¨ Contact

For questions, feedback, or collaboration inquiries:

πŸ“§ support@polar-dynamix.com
🌐 www.polar-dynamix.com