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S May 14, 2019 at 14:01 history bounty ended CommunityBot
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May 9, 2019 at 11:09 history edited Oleg CC BY-SA 4.0
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S May 6, 2019 at 12:18 history bounty started Oleg
S May 6, 2019 at 12:18 history notice added Oleg Draw attention
May 4, 2019 at 22:01 history edited Oleg CC BY-SA 4.0
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May 3, 2019 at 15:34 comment added Oleg @WillieWong Thank you for the comments! You are totally right: if $u_0$ is continuous, then this case is described in Lunardi's boook and local existence follows e.g. by the Picard iterations. But what to do if $u_0\in L^2$?
May 3, 2019 at 15:16 comment added Willie Wong Your linked question is somewhat different. In the linked question $f$ is continuous but not Holder continuous, and the issue is local existence. In your case since $f$ is Lipschitz in $u$, you should be able to get local existence for $C^0$ initial data just using Picard iteration. Your dissipativity condition should give you also a priori, time-dependent upper bounds on $|u|$ using just the maximum principle, if I am not mistaken. This should give you most things you need for what you want.
May 3, 2019 at 15:00 comment added Willie Wong @MichaelRenardy: is it really true? If $f$ is independent of $z$, the putative inequality would read $0 \leq C - C|z_1 - z_2|^2$ for all $z_1, z_2$, which certainly is not always holding. The condition assumed seems to me to be requiring $f$ to be asymptotically in $z$ behaving like a strictly concave function.
May 3, 2019 at 11:12 history edited Oleg CC BY-SA 4.0
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May 3, 2019 at 11:01 history edited Oleg CC BY-SA 4.0
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May 3, 2019 at 10:55 comment added Oleg @MichaelRenardy Thanks for your comment, but I also assumed that $f$ is continuous in $t$ in $x$. In this case if $f$ does not depend on $u$, then it is bounded on $[0,T]\times \mathbb{T}^d$ and there is no blow-up.
May 3, 2019 at 10:07 history edited Oleg CC BY-SA 4.0
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May 3, 2019 at 9:43 history edited Oleg CC BY-SA 4.0
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May 3, 2019 at 9:42 comment added Oleg @user35593 Yes, $u_0$ should ideally be in $L_2$, but existence for continuous $u_0$ would also be fine for me.
May 3, 2019 at 6:24 comment added user35593 Do you have some initial conditions as well?
May 2, 2019 at 20:56 history edited Oleg CC BY-SA 4.0
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May 2, 2019 at 20:37 history edited Oleg
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May 2, 2019 at 13:54 history asked Oleg CC BY-SA 4.0