enriquelvarez
Mechanical
- Jan 25, 2007
- 20
Hi everybody again,
I'm trying to understand the difference between two parametres related to calculating resonance frequencies in a modal analysis.
I'm doing a modal analysis of a wetted structure. The fluid is air. Three optional parametres can be chosen: "PARAM, VMOPT,1","PARAM, VMOPT,2" and default option is "PARAM, VMOPT,0"
What I got is: option 2 calculates dry frequencies and afer that, fluid mass is included in mass matrix and wet frequencies are calculated. On the other hand, option 1 includes fluid mass from the beggining and wet frequencies are calculated. Effective mass from both options are different.
In addition, using default option (option 0), I got the same results as option 1 concerning frequencies and effective mass.
I suppose that effective mass from options 0 and 1 includes fluid mass
So questions are:
1-What is the difference between "PARAM,VMOPT,1" and "PARAM,VMOPT,0"?
2-What is the effective mass results given by "PARAM,VMOPT,2"?
Thanks very much
Enrique
I'm trying to understand the difference between two parametres related to calculating resonance frequencies in a modal analysis.
I'm doing a modal analysis of a wetted structure. The fluid is air. Three optional parametres can be chosen: "PARAM, VMOPT,1","PARAM, VMOPT,2" and default option is "PARAM, VMOPT,0"
What I got is: option 2 calculates dry frequencies and afer that, fluid mass is included in mass matrix and wet frequencies are calculated. On the other hand, option 1 includes fluid mass from the beggining and wet frequencies are calculated. Effective mass from both options are different.
In addition, using default option (option 0), I got the same results as option 1 concerning frequencies and effective mass.
I suppose that effective mass from options 0 and 1 includes fluid mass
So questions are:
1-What is the difference between "PARAM,VMOPT,1" and "PARAM,VMOPT,0"?
2-What is the effective mass results given by "PARAM,VMOPT,2"?
Thanks very much
Enrique