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This research focuses on the control of cumuliform cloud formation using computational fluid dynamics, aiming to generate naturally-looking clouds with desired shapes. The method involves feedback control and a geometric potential field to adjust the amount of latent heat and water vapor, influencing the cloud growth process.
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Feedback Control of Cumuliform Cloud Formation based on Computational Fluid Dynamics Yoshinori Dobashi (Hokkaido University) Katsutoshi Kusumoto (Hokkaido University) Tomoyuki Nishita (The University of Tokyo) Tsuyoshi Yamamoto (Hokkaido University)
Overview • Introduction • Previous Work • Overview of Our Method • Details of Our Method • Results • Conclusions
Introduction • Visual simulation of natural phenomena • Fire, smoke , water, clouds, etc.. • Computational Fluid Dynamics • Realistic shape and motion [Miyazaki 02] [Enright 02] [Nguyen 02] [Fedkiw 01]
Introduction • Applications include movies and commercial films • Requiring desired shapes and motion • Controlling fluid simulation • for smoke and water Our research focuses on clouds [Miyazaki 02] [Enright 02] [Nguyen 02] [Fedkiw 01]
Introduction • Clouds simulation using CFD [Miyazaki 02] • Realistic clouds • Many physical parameters(temperature, water vapor, etc..) • Difficult to generate desired shape Goal:Generation of clouds with desired shape • Controlling cloud formation process • Naturally-looking clouds with desired shape
Features of Our Method video
Overview • Introduction • Previous Work • Overview of Our Method • Details of Our Method • Results • Conclusions
Controlling fluid simulation Previous Work • Keyframe Control of Smoke Simulation • [Treuille et al 03] • Fluid Control Using the Adjoint Method • [McNamara et al 04] • Target driven smoke animation • [Fattal et al 04]
Previous Work • Controlling fluid simulation • Controlling Fluid Animation with Geometric Potential [Kim and Hong 04] • No methods for cloud simulation • Intended for unnatural shape • No considerations for physical processes for cloud formation • phase transition, adiabatic cooling... • Taming liquids for rapidly changing targets [Shi et al 05] • Detail-Preserving Fluid Control [Thürey et al 06]
Overview • Introduction • Previous Work • Overview of Our Method • Details of Our Method • Results • Conclusions
density, velocity, etc Overview of Our Method • Simulation of cloud formation • Atmospheric fluid dynamics [Miyazaki et al 02] • Cumuliform cloud formation • No wind • Control method • Feedback control • Geometric potential field
Simulation of Cloud Formation Ground is heated by the sun.
buoyancy force air parcels Simulation of Cloud Formation Air parcels start to move upward.
Simulation of Cloud Formation Temperature of air parcels decreases. adiabatic expansion/ cooling
(vapor cloud) Simulation of Cloud Formation Clouds are generated due to phase transition phase transition
(vapor cloud) Simulation of Cloud Formation latent heatis liberated due to phase transition phase transition
(vapor cloud) Simulation of Cloud Formation latent heatis liberated due to phase transition phase transition additional buoyancy
(vapor cloud) Simulation of Cloud Formation latent heat is liberated due to phase transition phase transition additional buoyancy further cloud growth
(vapor cloud) Simulation of Cloud Formation latent heat is liberated due to phase transition phase transition The cloud growth is controlled by adjusting the amount of latent heat additional buoyancy further cloud growth
Simulation of cloud formation • Atmospheric fluid dynamics [Miyazaki et al 02] • Cumuliform cloud formation • No wind • Control method • Feedback control • Geometric potential field density, velocity, etc Overview of Our Method
center of simulation space 3D Target Shape from Contours • Drawing contours target shape plane including center • Projecting contours • Creating target shape [Igarashi et al 99] desired contour screen viewpoint simulation space
minimize Our Control Method • Feedback control • Geometric potential field target shape difference from the highest point simulated clouds
Feedback Control • Latent heat controller • Water vapor supplier Htarget Hc / Htarget Hc
Feedback Control • Latent heat controller • Water vapor supplier Htarget Hc / Htarget Hc latent heat controller
Feedback Control • Latent heat controller • Water vapor supplier No latent heat without phase transitions from vapor to clouds Hc / Htarget increase latent heat latent heat controller
Feedback Control • Latent heat controller • Water vapor supplier water vapor supplier Hc / Htarget increase latent heat latent heat controller
Feedback Control • Latent heat controller • Water vapor supplier water vapor supplier add water vapor • Generation of clouds • Cloud development Hc / Htarget increase latent heat latent heat controller
water vapor supplier water vapor supplier water vapor supplier water vapor supplier water vapor supplier water vapor supplier water vapor supplier water vapor supplier water vapor supplier water vapor supplier water vapor supplier water vapor supplier water vapor supplier water vapor supplier latent heat controller latent heat controller latent heat controller latent heat controller latent heat controller latent heat controller latent heat controller latent heat controller latent heat controller latent heat controller latent heat controller latent heat controller latent heat controller latent heat controller Feedback Control • Latent heat controller • Water vapor supplier
water vapor supplier water vapor supplier water vapor supplier water vapor supplier water vapor supplier water vapor supplier water vapor supplier water vapor supplier water vapor supplier water vapor supplier water vapor supplier water vapor supplier water vapor supplier water vapor supplier latent heat controller latent heat controller latent heat controller latent heat controller latent heat controller latent heat controller latent heat controller latent heat controller latent heat controller latent heat controller latent heat controller latent heat controller latent heat controller latent heat controller Feedback Control • Latent heat controller • Water vapor supplier
potential horizontal component of gradient Geometric Potential Field • Horizontal force around boundaries of target shape • Preventing clouds from growing outside target shape
potential horizontal component of gradient Geometric Potential Field • Horizontal force around boundaries of target shape • Preventing clouds from growing outside target shape • Feedback controller: vertical extent • Geometric potential field: horizontal extent
Overview • Introduction • Previous Work • Overview of Our Method • Details of Our Method • Results • Conclusions
Details of Our Method • Formulation of our feedback controller • Feedback controller • Geometric potential field
Details of Our Method • Formulation of our feedback controller • Feedback controller • Geometric potential field
Details of Our Method • Formulation of our feedback controller • Feedback controller • Geometric potential field
Cloud Formation • Velocity of atmosphere • NS equation + buoyancy force • Temperature of atmosphere • Adiabatic cooling, latent heat, heat from ground • Water vapor and water droplet (clouds) • Phase transition between vapor and droplets
: time : external force : velocity : pressure Velocity of Atmosphere • Incompressible Navier-Stokes Equation (buoyancy force)
Buoyancy and Temperature • Thermal buoyancy : temperature : ambient temperature : buoyancy coeff. : upward vertical vector
Buoyancy and Temperature • Thermal buoyancy : temperature : ambient temperature : buoyancy coeff. : upward vertical vector • Temperature : latent heat coeff. : amount of generated clouds : adiabatic lapse rate : vertical component of velocity : heat supplied from ground
Buoyancy and Temperature • Thermal buoyancy : temperature : ambient temperature : buoyancy coeff. : upward vertical vector • Temperature : latent heat coeff. : amount of generated clouds : adiabatic lapse rate : vertical component of velocity : heat supplied from ground
Buoyancy and Temperature • Thermal buoyancy : temperature : ambient temperature : buoyancy coeff. : upward vertical vector • Temperature : latent heat coeff. : amount of generated clouds : adiabatic lapse rate : vertical component of velocity : heat supplied from ground
Buoyancy and Temperature • Thermal buoyancy : temperature : ambient temperature : buoyancy coeff. : upward vertical vector • Temperature amount of latent heat : latent heat coeff. : amount of generated clouds : adiabatic lapse rate : vertical component of velocity : heat supplied from ground
Buoyancy and Temperature • Thermal buoyancy : temperature : ambient temperature : buoyancy coeff. : upward vertical vector • Temperature control (latent heat controller) : latent heat coeff. : amount of generated clouds : adiabatic lapse rate : vertical component of velocity : heat supplied from ground
Buoyancy and Temperature • Thermal buoyancy : temperature : ambient temperature : buoyancy coeff. : upward vertical vector change in buoyancy • Temperature control (latent heat controller) : latent heat coeff. : amount of generated clouds : adiabatic lapse rate : vertical component of velocity : heat supplied from ground
Phase transition : cloud density : vapor density : clouds generated by phase transition Water vapor and Water Droplet water droplet: water vapor:
Phase transition : cloud density : vapor density : clouds generated by phase transition Water vapor and Water Droplet water droplet: water vapor: control (water vapor supplier)
Details of Our Method • Formulation of our controller • Feedback controller • latent heat controller • water vapor supplier • Geometric potential field
Details of Our Method • Formulation of our controller • Feedback controller • latent heat controller • water vapor supplier • Geometric potential field
Latent Heat Controller • PI Control (Proportional Integral Control) • Proportional control updates latent heat according to difference • Integral control updates latent heat according to accumulated difference difference latent heat coefficient P controller I controller ( KP: proportional gain, KI: integral gain )
Latent Heat Controller • PI Control (Proportional Integral Control) • PI Control height of clouds target shape P controller target height difference small gaps are left clouds time