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On blow-up criteria for a coupled chemotaxis fluid model


We consider a coupled chemotaxis fluid model and prove some blow-up criteria of the local strong solution.


We consider the following coupled chemotaxis fluid model [1]:

$$\begin{aligned}& u_{t}+(u\cdot\nabla) u+\nabla\pi-\Delta u+n\nabla\phi=0, \end{aligned}$$
$$\begin{aligned}& \operatorname{div}u=0, \end{aligned}$$
$$\begin{aligned}& n_{t}+(u\cdot\nabla)n-\Delta n=-\nabla\cdot\bigl(n\chi(p)\nabla p \bigr), \end{aligned}$$
$$\begin{aligned}& p_{t}+(u\cdot\nabla)p=-nf(p), \end{aligned}$$
$$\begin{aligned}& (u,n,p) (x,0)=(u_{0},n_{0},p_{0}) (x) \quad \mbox{in } \mathbb{R}^{3}. \end{aligned}$$

Here u denotes the velocity vector field of the fluid and π is the pressure scalar, p and n denote the concentration of oxygen and bacteria, respectively. ϕ is the gravitation force. \(f(p)\geq f(0)=0\) and \(\chi(p)\geq0\) are two given smooth functions of p.

When \(\phi=0\), (1.1) and (1.2) are the well-known Navier-Stokes system. Kozono et al. [2] and Kozono and Shimada [3] proved the following blow-up criteria:

$$\begin{aligned}& u\in L^{2}\bigl(0,T;\dot{B}^{0}_{\infty,\infty} \bigr), \end{aligned}$$
$$\begin{aligned}& u\in L^{\frac{2}{1-\theta}}\bigl(0,T;\dot{B}^{-\theta}_{\infty,\infty} \bigr)\quad \mbox{with }0< \theta< 1, \end{aligned}$$
$$\begin{aligned}& \omega:=\operatorname{curl}u\in L^{1}\bigl(0,T; \dot{B}^{0}_{\infty,\infty}\bigr). \end{aligned}$$

Here \(\dot{B}^{s}_{p,q}\) denotes the homogeneous Besov space. Zhang et al. [4] showed the following blow-up criterion in terms of pressure:

$$ \pi\in L^{\frac{2}{2+r}}\bigl(0,T;\dot{B}^{r}_{\infty,\infty} \bigr)\quad\mbox{with }{-}1\leq r\leq1. $$

When \(u=\nabla\phi=0\), (1.3) and (1.4) are the Keller-Segel model which was studied in [5, 6].

Very recently, Chae et al.[7] showed the local well-posedness of smooth solutions to problem (1.1)-(1.5) and the following blow-up criterion:

$$ u\in L^{\frac{2q}{q-3}}\bigl(0,T;L^{q}\bigr)\quad \mbox{and}\quad n\in L^{2}\bigl(0,T;L^{\infty}\bigr)\quad \mbox{with }3< q\leq\infty. $$

The aim of this paper is to refine (1.10) further; we will prove the following.

Theorem 1.1

Let the initial data \((u_{0},n_{0},p_{0})\) be given in \(H^{l}\times H^{l-1}\times H^{l}\) for \(l>\frac{5}{2}\) and \(n_{0}\), \(p_{0}\geq0\) in \(\mathbb{R}^{3}\) and \(\int_{\mathbb{R}^{3}}n_{0}\,dx<\infty\). Suppose that ϕ is a smooth function. Let \((u, n, p)\) be a local smooth solution on \([0,\tilde{T})\) for some \(\tilde{T}\leq\infty\). If u satisfies (1.6) or (1.7) or (1.8) or π satisfies (1.9) (\(r=-1\)) and n satisfies

$$ n\in L^{2}\bigl(0,T;L^{\infty}\bigr) $$

with \(\tilde{T}\leq T<\infty\), then the solution \((u, n ,p)\) can be extended beyond \(T>0\).

Corollary 1.1

If u satisfies (1.6) or (1.7) or (1.8) or π satisfies (1.9) and p satisfies

$$ \nabla p\in L^{\frac{2q}{q-3}}\bigl(0,T;L^{q}\bigr)\quad \textit{with }3< q\leq\infty, $$

with \(\tilde{T}\leq T<\infty\), then the solution \((u, n ,p)\) can be extended beyond \(T>0\).

Remark 1.1

By the very same calculations as those in Zhou [8], we can prove the following blow-up criteria:

$$ \pi\in L^{\frac{2q}{2q-3}}\bigl(0,T;L^{q}\bigr)\quad \mbox{with }3/2< q\leq\infty, $$


$$ \nabla\pi\in L^{\frac{2q}{3q-3}}\bigl(0,T;L^{q}\bigr)\quad \mbox{with }1< q\leq\infty, $$

and n satisfies (1.11). We omit the details here.


Here we recall the definitions and some properties of spaces.

Let \(\mathfrak{B}=\{\xi\in\mathbb{R}^{d}, \vert \xi \vert \le \frac{4}{3}\}\) and \(\mathfrak{C}=\{\xi\in\mathbb{R}^{d}, \frac{3}{4}\le \vert \xi \vert \le\frac{8}{3}\}\). Choose two nonnegative smooth radial functions χ, φ supported, respectively, in \(\mathfrak{B}\) and \(\mathfrak{C}\) such that

$$\begin{gathered} \chi(\xi)+\sum_{j\ge0}\varphi\bigl(2^{-j}\xi \bigr)=1,\quad\xi\in\mathbb{R}^{d}, \\ \sum_{j\in\mathbb{Z}}\varphi\bigl(2^{-j}\xi\bigr)=1, \quad\xi\in\mathbb {R}^{d}\setminus\{0\}. \end{gathered} $$

We denote \(\varphi_{j}=\varphi(2^{-j}\xi)\), \(h=\mathfrak{F}^{-1}\varphi \) and \(\tilde{h}=\mathfrak{F}^{-1}\chi\), where \(\mathfrak{F}^{-1}\) stands for the inverse Fourier transform. Then the dyadic blocks \(\Delta_{j}\) and \(S_{j}\) can be defined as follows:

$$\begin{gathered} \Delta_{j}f=\varphi\bigl(2^{-j}D\bigr)f=2^{jd} \int_{\mathbb{R}^{d}}h\bigl(2^{j}y\bigr)f(x-y)\,dy, \\ S_{j}f=\sum_{k\le j-1}\Delta_{k}f= \chi\bigl(2^{-j}D\bigr)f=2^{jd} \int_{\mathbb {R}^{d}}\tilde{h}\bigl(2^{j}y\bigr)f(x-y)\,dy. \end{gathered} $$

Formally, \(\Delta_{j}=S_{j}-S_{j-1}\) is a frequency projection to annulus \(\{\xi: C_{1}2^{j}\le \vert \xi \vert \le C_{2}2^{j}\}\), and \(S_{j}\) is a frequency projection to the ball \(\{\xi: \vert \xi \vert \le C2^{j}\}\). One can easily verify that, with our choice of φ,

$$\Delta_{j}\Delta_{k}f=0\quad \mbox{if } \vert j-k\vert \ge2\quad \mbox{and}\quad \Delta_{j}(S_{k-1}f\Delta_{k}f)=0 \quad \mbox{if }\vert j-k\vert \ge5. $$

With the introduction of \(\Delta_{j}\) and \(S_{j}\), let us recall the definition of the Besov space.

Definition 2.1

[9, 10]

Let \(s\in\mathbb{R}\), \((p,q)\in [1,\infty]^{2}\), the homogeneous space \(\dot{B}_{p,q}^{s}\) is defined by

$$\dot{B}_{p,q}^{s}=\bigl\{ f\in\mathfrak{S}'; \Vert f\Vert _{\dot {B}_{p,q}^{s}}< \infty\bigr\} , $$


$$ \Vert f\Vert _{\dot{B}_{p,q}^{s}}= \textstyle\begin{cases} (\sum _{j\in\mathbb{Z}}2^{sqj}\Vert \Delta_{j}f \Vert _{L^{p}}^{q})^{\frac{1}{q}},&\mbox{for } 1\le q< \infty, \\ \sup_{j\in\mathbb{Z}}2^{sj}\Vert \Delta_{j}f \Vert _{L^{p}},&\mbox{for } q=\infty, \end{cases} $$

and \(\mathfrak{S}'\) denotes the dual space of \(\mathfrak{S}=\{f\in \mathcal{S}(\mathbb{R}^{d}); \partial^{\alpha}\hat{f}(0)=0; \forall\alpha \in \mathbb{N}^{d} \mbox{ multi-index}\}\) and can be identified by the quotient space of \(\mathcal{S'}/\mathcal{P}\) with the polynomials space \(\mathcal{P}\).

Lemma 2.1


Let a measurable function π satisfy

$$\pi\in\dot{B}_{\infty,\infty}^{r}\bigl(\mathbb{R}^{3}\bigr) $$

for some r with \(-1\leq r\leq1\), then there exists a decomposition \(\pi:=\pi_{\ell}+\pi_{h}\) such that

$$\nabla^{2}\pi_{\ell}\in L^{\infty}\bigl( \mathbb{R}^{3}\bigr)\quad \textit{and}\quad \pi _{h}\in W^{-1,\infty}\bigl(\mathbb{R}^{3}\bigr), $$


$$\begin{aligned}& \bigl\Vert \nabla^{2}\pi_{\ell}\bigr\Vert _{L^{\infty}}^{\frac{1}{2}}+\Vert \pi_{h}\Vert _{ W^{-1,\infty}}^{2}\leq C\bigl(e+\Vert \pi \Vert _{\dot{B}_{\infty,\infty}^{r}}^{\frac{2}{2+r}}\bigr), \\& \Vert \pi_{\ell} \Vert _{L^{2}}\leq C\Vert \pi \Vert _{L^{2}}, \Vert \nabla\pi_{h}\Vert _{L^{2}}\leq C \Vert \nabla \pi \Vert _{L^{2}}. \end{aligned}$$

Proof of Theorem 1.1

This section is devoted to the proof of Theorem 1.1. Since local existence results have been proved in [7], we only need to prove a priori estimates.

To begin with, it is easy to see that

$$ n\geq0,\qquad 0\leq p\leq C,\qquad \int_{\mathbb{R}^{3}}n\,dx= \int_{\mathbb {R}^{3}}n_{0}\,dx< \infty. $$

Case 1. Let (1.6) and (1.11) hold true.

Testing (1.1) by u and using (1.2), we infer that

$$\begin{aligned} \frac{1}{2}\frac{d}{dt} \int_{\mathbb{R}^{3}}\vert u\vert ^{2}\,dx+ \int_{\mathbb{R}^{3}}\vert \nabla u\vert ^{2}\,dx =& \int _{\mathbb{R}^{3}}n\nabla\phi u\,dx \\ \leq&\Vert n\Vert _{L^{\infty}} \Vert \nabla\phi \Vert _{L^{2}} \Vert u\Vert _{L^{2}}, \end{aligned}$$

which leads to

$$ \Vert u\Vert _{L^{\infty}(0,T;L^{2})}+\Vert u\Vert _{L^{2}(0,T;H^{1})} \leq C. $$

In the following calculations, we will use the following elegant inequality [11, 12]:

$$\Vert \nabla u\Vert _{L^{4}}^{2}\leq C\Vert u\Vert _{\dot{B}_{\infty,\infty}^{0}}\Vert \Delta u\Vert _{L^{2}}. $$

Testing (1.1) by Δu, using (1.2) and the above inequality, we find that

$$\begin{aligned}& \frac{1}{2}\frac{d}{dt} \int_{\mathbb{R}^{3}}\vert \nabla u\vert ^{2}\,dx+ \int_{\mathbb{R}^{3}}\vert \Delta u\vert ^{2}\,dx \\& \quad = \int_{\mathbb{R}^{3}}(u\cdot\nabla)u\cdot\Delta u \,dx+ \int _{\mathbb{R}^{3}}n\nabla\phi\Delta u\,dx \\& \quad = \sum_{i,j} \int_{\mathbb{R}^{3}}u_{i}\partial_{i}u \,\partial_{j}^{2}u\,dx+ \int _{\mathbb{R}^{3}}n\nabla\phi\Delta u\,dx \\& \quad = -\sum_{i,j} \int_{\mathbb{R}^{3}}\partial_{j}u_{i} \,\partial_{i}u\partial _{j}udx+ \int_{\mathbb{R}^{3}}n\nabla\phi\Delta u\,dx \\& \quad \leq C\Vert \nabla u\Vert _{L^{4}}^{2}\Vert \nabla u\Vert _{L^{2}}+\Vert n\Vert _{L^{\infty}} \Vert \nabla\phi \Vert _{L^{2}}\Vert \Delta u\Vert _{L^{2}} \\& \quad \leq C\Vert u\Vert _{\dot{B}_{\infty,\infty}^{0}}\Vert \Delta u\Vert _{L^{2}}\Vert \nabla u\Vert _{L^{2}}+C\Vert n\Vert _{L^{\infty}} \Vert \Delta u\Vert _{L^{2}} \\& \quad \leq\frac{1}{2}\Vert \Delta u\Vert _{L^{2}}^{2}+C \Vert u\Vert _{\dot{B}_{\infty,\infty}^{0}}^{2}\Vert \nabla u\Vert _{L^{2}}^{2}+C\Vert n\Vert _{L^{\infty}}^{2}, \end{aligned}$$

which gives

$$ \Vert u\Vert _{L^{\infty}(0,T;H^{1})}+\Vert u\Vert _{L^{2}(0,T;H^{2})} \leq C. $$

By (1.10), this completes the proof of Case 1.

Case 2. Let (1.7) and (1.11) hold true.

Testing (1.1) by \(-\Delta u\), using (1.2) and the following inequalities [3, 11]:

$$\begin{aligned}& \Vert u\cdot\nabla u\Vert _{L^{2}}\leq C\Vert u \Vert _{\dot{B}_{\infty,\infty}^{-\theta}} \Vert u\Vert _{\dot {B}_{2,1}^{1+\theta}}, 0< \theta< 1, \end{aligned}$$
$$\begin{aligned}& \Vert u\Vert _{\dot{B}_{2,1}^{\theta}}\leq C\Vert u\Vert _{L^{2}}^{1-\theta} \Vert \nabla u\Vert _{L^{2}}^{\theta}, 0< \theta< 1, \end{aligned}$$

we derive

$$\begin{aligned}& \frac{1}{2}\frac{d}{dt} \int_{\mathbb{R}^{3}}\vert \nabla u\vert ^{2}\,dx+ \int_{\mathbb{R}^{3}}\vert \Delta u\vert ^{2}\,dx \\& \quad= \int_{\mathbb{R}^{3}}(u\cdot\nabla)u \cdot\Delta u \,dx+ \int_{\mathbb {R}^{3}}n\nabla\phi\Delta u\,dx \\& \quad\leq \Vert u\cdot\nabla u\Vert _{L^{2}}\Vert \Delta u\Vert _{L^{2}}+\Vert n\Vert _{L^{\infty}} \Vert \nabla \phi \Vert _{L^{2}}\Vert \Delta u\Vert _{L^{2}} \\& \quad\leq C\Vert u\Vert _{\dot{B}_{\infty,\infty}^{-\theta }}\Vert \nabla u\Vert _{L^{2}}^{1-\theta} \Vert \Delta u\Vert _{L^{2}}^{1+\theta}+C \Vert n\Vert _{L^{\infty}} \Vert \Delta u\Vert _{L^{2}} \\& \quad\leq\frac{1}{2}\Vert \Delta u\Vert _{L^{2}}^{2}+C \Vert u\Vert _{\dot{B}_{\infty,\infty}^{\frac{2}{1-\theta}}} \Vert \nabla u\Vert _{L^{2}}^{2}+C \Vert n\Vert _{L^{\infty}}^{2}, \end{aligned}$$

which yields (3.3); this completes the proof of Case 2 again by (1.10).

Case 3. Let (1.8) and (1.11) hold true.

Testing (1.1) by \(-\Delta u\), using (1.2), we deduce that

$$ \begin{aligned}[b] &\frac{1}{2}\frac{d}{dt} \int_{\mathbb{R}^{3}}\vert \nabla u\vert ^{2}\,dx+ \int_{\mathbb{R}^{3}}\vert \Delta u\vert ^{2}\,dx \\ &\quad=-\sum_{i,j} \int_{\mathbb{R}^{3}}\partial_{j}u_{i} \,\partial_{i}u\partial _{j}udx+ \int_{\mathbb{R}^{3}}n\nabla\phi\Delta u\,dx \\ &\quad=:I_{1}+ \int_{\mathbb{R}^{3}}n\nabla\phi\Delta u \,dx. \end{aligned} $$

By the very same calculations as those in [13], we get

$$ I_{1}\leq\frac{1}{8}\Vert \Delta u\Vert _{L^{2}}^{2}+C\Vert \nabla u\Vert _{L^{2}}^{2}+C \Vert \nabla u\Vert _{\dot {B}_{\infty,\infty}^{0}}\Vert \nabla u\Vert _{L^{2}}^{2}\operatorname{log}\bigl(e+\Vert \nabla u\Vert _{L^{2}}^{2}\bigr). $$

Inserting (3.7) into (3.6) and solving the resulting inequality, we arrive at (3.3). This completes the proof of Case 3.

Case 4. Let (1.9) (\(r=-1\)) and (1.11) hold true.

Testing (1.1) by \(\vert u\vert ^{2}u\) and using (1.2), we observe that

$$ \begin{aligned}[b] &\frac{1}{4}\frac{d}{dt} \int_{\mathbb{R}^{3}}\vert u\vert ^{4}\,dx+ \int_{\mathbb{R}^{3}}\vert u\vert ^{2}\vert \nabla u\vert ^{2}\,dx+\frac{1}{2} \int_{\mathbb{R}^{3}}\bigl\vert \nabla \vert u\vert ^{2} \bigr\vert ^{2}\,dx \\ &\quad=- \int_{\mathbb{R}^{3}}(u\cdot\nabla)\pi \vert u\vert ^{2}\,dx- \int_{\mathbb{R}^{3}}n\nabla\phi \vert u\vert ^{2} u\,dx \\ &\quad=:I_{2}+I_{3}. \end{aligned} $$

\(I_{3}\) can be bounded as follows:

$$ I_{3}\leq \Vert n\Vert _{L^{\infty}} \Vert \nabla \phi \Vert _{L^{4}}\Vert u\Vert _{L^{4}}^{3}. $$

We bounded \(I_{2}\) as follows:

$$\begin{aligned} I_{2}&= \int_{\mathbb{R}^{3}}\pi u \cdot\nabla \vert u\vert ^{2}\,dx \\ &\leq \Vert \pi \Vert _{L^{4}}\Vert u\Vert _{L^{4}}\bigl\Vert \nabla \vert u\vert ^{2}\bigr\Vert _{L^{2}} \\ &\leq \Vert \pi \Vert _{\dot{B}_{\infty,\infty}^{-1}}^{\frac {1}{2}}\Vert \nabla\pi \Vert _{L^{2}}^{1/2}\Vert u\Vert _{L^{4}}\bigl\Vert \nabla \vert u\vert ^{2}\bigr\Vert _{L^{2}} \\ &\leq \Vert \pi \Vert _{\dot{B}_{\infty,\infty}^{-1}}^{\frac {1}{2}}\bigl(\Vert u\cdot\nabla u\Vert _{L^{2}}+\Vert n\nabla \phi \Vert _{L^{2}} \bigr)^{1/2}\Vert u\Vert _{L^{4}}\bigl\Vert \nabla \vert u \vert ^{2}\bigr\Vert _{L^{2}} \\ &\leq \Vert \pi \Vert _{\dot{B}_{\infty,\infty}^{-1}}^{\frac {1}{2}}\bigl(\bigl\Vert u \vert \nabla u\vert \bigr\Vert _{L^{2}}+\Vert n\Vert _{L^{\infty}}\bigr)^{1/2}\Vert u\Vert _{L^{4}}\bigl\Vert \nabla \vert u\vert ^{2}\bigr\Vert _{L^{2}} \\ &\leq\frac{1}{8}\bigl\Vert \nabla \vert u\vert ^{2}\bigr\Vert _{L^{2}}^{2}+\frac{1}{8}\bigl\Vert u\vert \nabla u\vert \bigr\Vert _{L^{2}}^{2}+C\Vert \pi \Vert _{\dot{B}_{\infty,\infty }^{-1}}^{2}\Vert u\Vert _{L^{4}}^{4}+C \Vert n\Vert _{L^{\infty}}^{2}, \end{aligned}$$

where we have used the elegant inequality [11, 12]

$$ \Vert \pi \Vert _{L^{4}}^{2}\leq C\Vert \pi \Vert _{\dot {B}_{\infty,\infty}^{-1}}\Vert \nabla\pi \Vert _{L^{2}}, $$

and the pressure estimate

$$ \Vert \nabla\pi \Vert _{L^{2}}\leq C\bigl(\Vert u\cdot \nabla u\Vert _{L^{2}}+\Vert n\nabla\phi \Vert _{L^{2}}\bigr). $$

Inserting (3.9) and (3.10) into (3.8) and using the Gronwall inequality, we conclude that

$$ \Vert u\Vert _{{L^{\infty}}(0,T;{L^{4}})}\leq C. $$

By (1.10), this completes the proof of Case 4.

Proof of Corollary 1.1

Testing (1.3) by \(n^{m-1}\) (\(m\geq2\)), using (1.2) and (3.1) and denoting \(w:=n^{\frac{m}{2}}\), we have

$$\begin{aligned}& \frac{1}{m}\frac{d}{dt} \int_{\mathbb{R}^{3}}w^{2}\,dx+\frac{4(m-1)}{m^{2}} \int _{\mathbb{R}^{3}}\vert \nabla w\vert ^{2}\,dx \\& \quad\leq C\biggl\vert \int\chi(p)\nabla p\cdot w\nabla w \,dx\biggr\vert \\& \quad\leq C\Vert \nabla p\Vert _{L^{q}}\Vert w\Vert _{L^{\frac{2q}{q-2}}}\Vert \nabla w\Vert _{L^{2}} \\& \quad\leq C\Vert \nabla p\Vert _{L^{q}}\Vert w\Vert _{L^{2}}^{1-\frac{3}{q}}\Vert \nabla w\Vert _{L^{2}}^{1+\frac{3}{q}} \\& \quad\leq\frac{m-1}{m^{2}}\Vert \nabla w\Vert _{L^{2}}^{2}+C \Vert \nabla p\Vert _{L^{q}}^{\frac{2q}{q-3}}\Vert w\Vert _{L^{2}}^{2}, \end{aligned}$$

which implies

$$ \Vert n\Vert _{{L^{\infty}}(0,T;{L^{m}})}\leq C\quad\mbox{for }m>2. $$

Here we used the Gagliardo-Nirenberg inequality

$$ \Vert w\Vert _{L^{\frac{2q}{q-2}}}\leq C\Vert w\Vert _{L^{2}}^{1-\frac{3}{q}}\Vert \nabla w\Vert _{L^{2}}^{\frac {3}{q}} \quad\mbox{with }3< q\leq\infty. $$

Now, since the proofs of other cases are very similar to those in Case 1, Case 2, Case 3 and Case 4, we only prove the following case: Let (1.9) (\(-1< r\leq1\)) and (1.12) hold true.

We still have (3.8) and (3.9).

Using Lemma 2.1, (3.11), (3.12) and the pressure estimate

$$ \begin{aligned}[b] \Vert \pi \Vert _{L^{2}}& \leq C\bigl(\Vert u\Vert _{L^{4}}^{2}+\bigl\Vert (- \Delta)^{-\frac{1}{2}}(n\nabla\phi)\bigr\Vert _{L^{2}}\bigr) \\ &\leq C\bigl(\Vert u\Vert _{L^{4}}^{2}+\Vert n\nabla\phi \Vert _{L^{\frac{6}{5}}}\bigr) \\ &\leq C\bigl(\Vert u\Vert _{L^{4}}^{2}+1\bigr), \end{aligned} $$

. we bound \(I_{2}\) as follows:

$$ \begin{aligned}[b] I_{2}&=- \int_{\mathbb{R}^{3}}u\nabla\pi_{\ell} \vert u\vert ^{2}\,dx- \int_{\mathbb{R}^{3}}u\nabla\pi_{h}\vert u\vert ^{2}\,dx \\ &\leq \Vert \nabla\pi_{\ell} \Vert _{L^{4}}\Vert u\Vert _{L^{4}}^{3}+ \int_{\mathbb{R}^{3}}u\pi_{h}\nabla \vert u\vert ^{2}\,dx \\ &\leq \Vert \pi_{\ell} \Vert _{L^{2}}^{\frac{1}{2}}\bigl\Vert \nabla^{2}\pi_{\ell}\bigr\Vert _{L^{\infty}}^{{\frac{1}{2}}} \Vert u\Vert _{L^{4}}^{3}+\Vert u\Vert _{L^{4}} \Vert \pi _{h}\Vert _{L^{4}}\bigl\Vert \nabla \vert u \vert ^{2}\bigr\Vert _{L^{2}} \\ &\leq \Vert \pi_{\ell} \Vert _{L^{2}}^{\frac{1}{2}}\bigl\Vert \nabla^{2}\pi_{\ell}\bigr\Vert _{L^{\infty}}^{{\frac{1}{2}}} \Vert u\Vert _{L^{4}}^{4}+\Vert u\Vert _{L^{4}} \Vert \pi _{h}\Vert _{W^{-1,\infty}}^{\frac{1}{2}}\Vert \nabla \pi_{h}\Vert _{L^{2}}^{\frac{1}{2}}\bigl\Vert \nabla \vert u\vert ^{2}\bigr\Vert _{L^{2}} \\ &\leq\bigl\Vert \nabla^{2}\pi_{\ell}\bigr\Vert _{L^{\infty}}^{\frac {1}{2}}\bigl(\Vert u\Vert _{L^{4}}^{4}+1 \bigr)+C\Vert \pi_{h}\Vert _{W^{-1,\infty}}^{\frac{1}{2}}\bigl( \Vert u\cdot\nabla u\Vert _{L^{2}}+1\bigr)^{\frac{1}{2}}\Vert u \Vert _{L^{4}}\bigl\Vert \nabla \vert u\vert ^{2}\bigr\Vert _{L^{2}} \\ &\leq\frac{1}{8}\bigl\Vert \nabla \vert u\vert ^{2}\bigr\Vert _{L^{2}}^{2}+\frac{1}{8}\Vert u\cdot\nabla u \Vert _{L^{2}}^{2}+C\bigl(e+\Vert \pi \Vert _{B_{\infty,\infty}^{r}} \bigr)^{\frac {2}{2+r}}\bigl(\Vert u\Vert _{L^{4}}^{4}+1 \bigr)+C. \end{aligned} $$

Inserting (3.9) and (4.4) into (3.8), we obtain (3.13).

By the classical regularity theory of parabolic equations [14], it follows from (1.2), (1.3), (3.13) and (4.4) that

$$ \begin{aligned}[b] \Vert \nabla n\Vert _{L^{2}(0,T;L^{\tilde{r}})}&\leq C\bigl(1+\Vert un\Vert _{L^{2}(0,T;L^{\tilde{r}})}+\bigl\Vert n \chi(p)\nabla p\bigr\Vert _{L^{2}(0,T;L^{\tilde{r}})}\bigr) \\ &\leq C\bigl(1+\Vert u\Vert _{L^{\infty}(0,T;L^{4})}\Vert n\Vert _{L^{\infty}(0,T;L^{\frac{4\tilde{r}}{4-\tilde{r}}})}+\Vert n\Vert _{L^{\infty}(0,T;L^{\frac{q\tilde{r}}{q-\tilde {r}}})}\Vert \nabla p\Vert _{L^{2}(0,T;L^{q})}\bigr)\hspace{-10pt} \\ &\leq C \end{aligned} $$

for some \(3<\tilde{r}<4\) and \(\tilde{r}< q\).


$$ \Vert n\Vert _{L^{2}(0,T;L^{\infty})}\leq C. $$

This completes the proof.


  1. Tuval, I, Cisneros, L, Dombrowski, C, Wolgemuth, CW, Kessler, JO, Goldstein, RE: Bacterial swimming and oxygen transport near contact lines. Proc. Natl. Acad. Sci. USA 102, 2277-2282 (2005)

    Article  MATH  Google Scholar 

  2. Kozono, H, Ogawa, T, Taniuchi, Y: The critical Sobolev inequalities in Besov spaces and regularity criterion to some semi-linear evolution equations. Math. Z. 242(2), 251-278 (2002)

    MathSciNet  Article  MATH  Google Scholar 

  3. Kozono, H, Shimada, Y: Bilinear estimates in homogeneous Triebel-Lizorkin spaces and the Navier-Stokes equations. Math. Nachr. 276(1), 63-74 (2004)

    MathSciNet  Article  MATH  Google Scholar 

  4. Zhang, X, Jia, Y, Dong, BQ: On the pressure regularity criterion of the 3D Navier-Stokes equations. J. Math. Anal. Appl. 393(2), 413-420 (2012)

    MathSciNet  Article  MATH  Google Scholar 

  5. Corrias, L, Perthame, B, Zaag, H: Global solutions of some chemotaxis and angiogenesis systems in high space dimensions. Milan J. Math. 72, 1-28 (2004)

    MathSciNet  Article  MATH  Google Scholar 

  6. Perthame, B, Vasseur, A: Regularization in Keller-Segel type systems and the De Giorgi method. Commun. Math. Sci. 10(2), 463-476 (2012)

    MathSciNet  Article  MATH  Google Scholar 

  7. Chae, M, Kang, K, Lee, J: Global existence and temporal decay in Keller-Segel models coupled to fluid equations. Commun. Partial Differ. Equ. 39(7), 1205-1235 (2014)

    MathSciNet  Article  MATH  Google Scholar 

  8. Zhou, Y: On regularity criteria in terms of pressure for the Navier-Stokes equations in \(\mathbb{R}^{3}\). Proc. Am. Math. Soc. 134(1), 149-156 (2006)

    MathSciNet  Article  MATH  Google Scholar 

  9. Triebel, H: Theory of Function Spaces. Monographs in Mathematics, vol. 78. Birkhäuser Verlag, Basel (1983)

    Book  MATH  Google Scholar 

  10. Bahouri, H, Chemin, JY, Danchin, R: Fourier Analysis and Nonlinear Partial Differential Equations. Grundlehren der Mathematischen Wissenschaften [Fundamental Principles of Mathematical Sciences], vol. 343. Springer, Heidelberg (2011)

    MATH  Google Scholar 

  11. Machihara, S, Ozawa, T: Interpolation inequalities in Besov spaces. Proc. Am. Math. Soc. 131(5), 1553-1556 (2003)

    MathSciNet  Article  MATH  Google Scholar 

  12. Meyer, Y: Oscillating patterns in some nonlinear evolution equations. In: Mathematical Foundation of Turbulent Viscous Flows. Lecture Notes in Math., vol. 1871, pp. 101-187. Springer, Berlin (2006)

    Chapter  Google Scholar 

  13. Fan, J, Ozawa, T: Regularity criteria for the 3D density-dependent Boussinesq equations. Nonlinearity 22(3), 553-568 (2009)

    MathSciNet  Article  MATH  Google Scholar 

  14. Amann, H: Maximal regularity for nonautonomous evolution equations. Adv. Nonlinear Stud. 4, 417-430 (2004)

    MathSciNet  Article  MATH  Google Scholar 

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The authors would like to thank the referee for careful reading and helpful suggestions. This work is partially supported by Scientific Research Foundation of the Higher Education Institutions of Gansu Province (Grant No. 2015A-131) and TSNSF (Grant No. TSA1406).

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Xie, H., Ma, C. On blow-up criteria for a coupled chemotaxis fluid model. J Inequal Appl 2017, 30 (2017).

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  • Accepted:

  • Published:

  • DOI:


  • 22E46
  • 53C35
  • 57S20


  • Navier-Stokes
  • chemotaxis
  • oxygentaxis
  • regularity