[Invited Talk] Regularity and Long-Time Behavior for Hydrodynamic Flocking Models

There will be an invited talk.

Title: Regularity and Long-Time Behavior for Hydrodynamic Flocking Models
Speaker: Prof. Trevor Leslie (Univ. of Wisconsin-Madison)
Time: 2020 March 10th, 04:00pm~05:00pm
Place: 27-220
We consider the Euler Alignment model, a hydrodynamic analog of the discrete Cucker-Smale flocking ODE system. The salient feature of the Cucker-Smale model is the interaction of agents through a so-called “communication protocol” that tends to align the velocities of the agents; this alignment mechanism also drives the Euler Alignment PDEs. We discuss several of the different communication protocols treated in the literature and the corresponding wellposedness theory for the Euler Alignment model in each case. In the case of smooth, bounded protocols in one space dimension, it is possible to completely characterize the initial data leading to the existence of regular solutions, in terms of a certain pointwise balance between the initial velocity and the “total influence” from the density profile. This balance is captured by the sign of a certain quantity that we denote by e. Under the additional assumption of periodicity, a quantity closely related to e determines the long-time distortion of the density profile away from its average value.

HYKE Weekly Seminar

The following is the information for our weekly seminar in this semester.

Date : March 13th, 2020 ~ (every Friday)
Time: 09:00am ~ 12:00pm
Place: 27-116
Text: “A Course on Rough Paths” by Peter K. Friz and Martin Hairer

Schedule for presentations

3/13: Linglong Du (Ch 1)

3/20: Bora Moon (Ch 2)

3/27: So Young Park (Ch 3)

4/3: Min-Jun Choi (Ch 4)

4/10: Hyun Jin An (Ch 5)

4/24: Myeongju Kang (Ch 6)

5/1: Hangjun Jo (Ch 7)

5/8: Woojoo Shim (Ch 8)

5/15: Hansol Park (Ch 9)

If you want to join our seminar, please contact Myeongju Kang: bear0117@snu.ac.kr

Good News from Dr. Jeongho Kim

The S-OIL Foundation, founded by S-OIL, held ‘the 9th S-OIL Excellence Dissertation Award’ and ‘the 1st Next-Generation Scientist Award’ at its headquarters in Gongdeok-dong, Mapo-gu, Seoul, on December 17th, 2019. Dr. Jeongho Kim was selected for the Best Dissertation.

[Invited Talk] Derivation principle of BGK models

There will be an invited talk.

Title: Derivation principle of BGK models
Speaker: Prof. Stephane Brull (Univ. of Bordeaux)
Time: 2020 January 14th, 10:30am~11:20pm
Place: 27-116
In this talk we will present a derivation principle of BGK
models using the resolution of an entropy minimization problem.

The construction is based as on the introduction of relaxation
coefficients and a principle of entropy minimization under
constraints for moments. These free parameters are next ajusted to
transport coefficients when performing a Chapman-Engskog expansion
ip to Navier-Stokes. Firstly, the methodology will be explained and
illustrated for a monoatomic and polyatomic single gas.
Next the case of gas mixtures is considered. In this part, after
clarifying the Chapman-Engskog, a BGK model is derived. This BGK
model is proved to satisfy Fick and Newton laws. In a last part, we
will explain how to extend our model to reacting gas mixtures.

Workshop in Singapore

There was an workshop in Singapore named by “Quantum and Kinetic Problems: Modeling, Analysis, Numerics and Applications Workshop 3: Emergent Phenomena – from Kinetic Models to Social Hydrodynamics” from 16 December 2019 to 20.

[HYKE Seminar] Dynamics and control for multi-agent networked systems: A finite-difference approach

There will be a HYKE Seminar

Title: Dynamics and control for multi-agent networked systems: A finite-difference approach
Speaker: Dr.고동남 (University of Deusto, Spain)
Time: 2020 January 2nd, 9:00am~9:50am
Place: 27-116
We analyze the control properties of consensus models. Starting form the link between linear multi-agent systems and the spatial semi-discretization of parabolic equations, we compare the consensus model with the heat equation. The existing techniques for PDE control problems allow us to derive explicit estimates on the controllability and control cost. Our approach shows that the chain or circular network systems have the same properties as the 1D heat equation while we may extend it to the multi-dimensional or fractional type heat equations.