Dynamic Analysis of Slug Flow in CII

I have got few quries below:

1) How many number of slug cycles should be input for dynamic analysis of slug flow ? and is it depend upon type of slug ( like repeating & overlapping) ?

Because when we input one slug cycle for spectrum generation the DLF limits to value of 2 and when we input more than one number slug cycles the DLF value is more than 2.

2) What is the limliting value of DLF for dynamic analysis of slug flow and why ?

3) How does Caesar calculate DLF?

4) In which method we should carry out slug flow analysis either in time history or spectrum method?

Thanks in advance.

Regards,
AAD

1) That depends on your degree of certainty regarding the slugs. From an analysis point of view, I'd suggest a time history analysis if you start loading the system with mulitple slugs. This will be more complicated, but I don't think a response spectrum analysis can do this justice if you have more than one slug.

2) The limiting DLF value for a single impact load is 2 (from dynamic theory). Once you have multiple impacts, this limit is no longer applicable.

3) There is a big article in the November 1994 newsletter on how this is computed.

4) For a single slug I think the spectrum method is a better approach. However, regardless of what you do, your results are only as good as your estimate of the slug.

Thank you richard for your useful reply.
I have got few queries concerning to single slug as you mention.

Slug Duration 82.32 millisecond
Slug Periodicity 120.17 millisecond
Slug Force 60.83 kg




Sr.No. | Time | Force |
___________________________________________
1 | 0 | 60.83 | Beginning Of 1st Cycle
__________________________________________
2 | 82.32 | 60.83 |
__________________________________________
3 | 83 | 0 |
__________________________________________
4 | 120.17 | 0 |
________________________________________________________________________
5 | 121 | 60.83 | Beginning Of 2nd Cycle
__________________________________________
6 | 203.02 | 60.83 |
__________________________________________
7 | 203 | 0 |
__________________________________________
8 | 240.34 | 0 |
__________________________________________________________________________
9 | 241 | 60.83 | Beginning Of 3rd Cycle
___________________________________________
10 | 322.66 | 60.83 |
__________________________________________
11 | 323 | 0 |
__________________________________________
12 | 360.51 | 0 |
__________________________________________

By reviewing above time vs force profile can you advise us we can categorize this as single slug or multiple slug?

If above profile is of single slug type then how many number of slug cycles should be input in CII.Also if it is single type then we have to input in spectrum method or in time history method ?

If above profile is of single slug type then can you provide multiple slug type profile.( any case)

Your describing multiple impulses, multiple slugs. For a response spectrum approach, you can model one cycle per load case.