﻿ Sample Problems > Usage > Moving_Mesh > 2d_blob_position

# 2d_blob_position

Navigation:  Sample Problems > Usage > Moving_Mesh >

# 2d_blob_position

{ 2D_BLOB_POSITION.PDE

This problem illustrates moving meshes in 2D.

A circular boundary shrinks and grows sinusoidally in time.

The mesh coordinates are solved directly, without a mesh velocity variable.

See 2D_BLOB_VELOCITY.PDE for a version that uses mesh velocity variables.

}

TITLE 'Pulsating circle in 2D - position specification'

COORDINATES

cartesian2

VARIABLES

Phi           { the temperature }

Xm = MOVE(x) { surrogate X }

Ym = MOVE(y) { surrogate Y }

DEFINITIONS

K = 1         { default conductivity }

R0 = 0.75     { initial blob radius }

Um = dt(Xm)

Vm = dt(Ym)

INITIAL VALUES

Phi = (y+1)/2

EULERIAN EQUATIONS

BOUNDARIES

REGION 1 'box'

START(-1,-1)

VALUE(Phi)=0

VELOCITY(Xm)=0 VELOCITY(Ym)=0

LINE TO (1,-1)

NATURAL(Phi)=0

LINE TO (1,1)

VALUE(Phi)=1

LINE TO (-1,1)

NATURAL(Phi)=0

LINE TO CLOSE

REGION 2 'blob' { the embedded blob }

k = 0.001

START 'ring' (R0,0)

VELOCITY(Xm) = -0.25*sin(t)*x/r

VELOCITY(Ym) = -0.25*sin(t)*y/r

ARC(CENTER=0,0) ANGLE=360 TO CLOSE

TIME 0 TO 2*pi

MONITORS

for cycle=1

grid(x,y)

contour(phi)

PLOTS

FOR T = 0 BY pi/20 TO 2*pi

GRID(x,y)

CONTOUR(Phi)  notags nominmax