This paper deals with the initial-boundary value problem for a Keller–Segel system with rotation
{
u
t
=
Δ
u
−
∇
⋅
(
u
S
θ
∇
v
)
,
x
∈
Ω
,
t
>
0
,
0
=
Δ
v
−
v
+
u
,
x
∈
Ω
,
t
>
0
,
with zero-flux boundary condition for u and zero-Neumann boundary condition for v, where Ω is a bounded domain in
R
2
with smooth boundary
∂
Ω
,
S
θ
=
[
cos
θ
−
sin
θ
sin
θ
cos
θ
]
,
is a rotation matrix with
θ
∈
(
−
π
2
,
π
2
)
. We show that:
Let
Ω
⊂
R
2
be a general smooth bounded domain.
If
m
>
8
π
cos
θ
, then there exists nonnegative initial data u
0 satisfying
∫
Ω
u
0
d
x
=
m
, such that the corresponding nonradial solution of system (*) blows up in finite time and the blow-up point lies in Ω.
If
m
>
4
π
cos
θ
and
∂
Ω
contains a line segment, then there exists nonnegative initial data u
0 satisfying
∫
Ω
u
0
d
x
=
m
, such that the corresponding nonradial solution of system (*) blows up in finite time and the blow-up point lies on the line segment of
∂
Ω
.
Let
Ω
=
B
R
(
0
)
be a disc in
R
2
with radius R > 0 centered at origin. Although there is a rotation effect in system (*), solutions still preserve radial symmetry of initial data. If nonnegative radially symmetric initial data u
0 satisfies
∫
Ω
u
0
d
x
<
8
π
cos
θ
, then the corresponding radial solution of system (*) exists globally in time and is globally bounded.