pressure and fortran [Fortran]

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From: Uno on 5 Jun 2010 06:01

[normally, I would put OT in the subject.
I hope that this forum tolerates wildly errant source
regarding the gulf spill until it is less errant]

What silly thing have I done here so as to f up the output?

Dir for this script: E:\fortran_stuff\
E:\fortran_stuff>gfortran -Wall -Wextra p1.f90 -o out.exe
e:/fortran_
E:\fortran_stuff>gfortran -Wall -Wextra p1.f90 -o out.exe
e:/fortran_stuff/bin/../lib/gcc/x86_64-pc-mingw32/4.6.0/../../../../x86_64-pc-mi
ngw32/bin/ld.exe: cannot find -lgfortran
e:/fortran_stuff/bin/../lib/gcc/x86_64-pc-mingw32/4.6.0/../../../../x86_64-pc-mi
ngw32/bin/ld.exe: cannot find -lgcc
e:/fortran_stuff/bin/../lib/gcc/x86_64-pc-mingw32/4.6.0/../../../../x86_64-pc-mi
ngw32/bin/ld.exe: cannot find -lgcc
collect2: ld returned 1 exit status

E:\fortran_stuff>
print *, "atmos is ", atmos

endprogram
! gfortran -Wall -Wextra p1.f90 -o out.exe

implicit none

real :: mile_in_feet, atm_per_mile, atmos

mile_in_feet = 5280
atm_per_mile = 32.808399169

atmos = mile_in_feet / atm_per_mile

print *, "atmos is ", atmos

endprogram
! gfortran -Wall -Wextra p1.f90 -o out.exe

q1) Consider a half-inch copper pipe. Temperature is constant. If you
ran it for a minute into a pool, you would get a certain volume, say, x.
If you ran it for a minute at 32.8 ft below water level, what volume
of spewed water results?

q2) How would this vary if salt were added in the amounts of the gulf
of mexico?

--
Uno

From: robin on 5 Jun 2010 07:10

From: Ron Shepard on 5 Jun 2010 13:26

In article <86ulj7Ff3dU1(a)mid.individual.net>, Uno <merrilljensen(a)q.com>
wrote:

> implicit none
>
> real :: mile_in_feet, atm_per_mile, atmos
>
> mile_in_feet = 5280

This is feet per mile, right?

> atm_per_mile = 32.808399169

This is feet per atmosphere, right?

>
> atmos = mile_in_feet / atm_per_mile

This is atmospheres per mile, right? Your variable names are a little
confusing.

>
> print *, "atmos is ", atmos
>
> endprogram
> ! gfortran -Wall -Wextra p1.f90 -o out.exe
>
> q1) Consider a half-inch copper pipe. Temperature is constant. If you
> ran it for a minute into a pool, you would get a certain volume, say, x.
> If you ran it for a minute at 32.8 ft below water level, what volume
> of spewed water results?

You cannot know. If the pressure within the pipe is greater than the
pressure at 32.8 ft, then the liquid will continue to flow, but at a
slower rate. If the pressure within the pipe is less than the pressure
at 32.8 ft, then it will flow in the opposite direction.

So you need an additional important piece of information to answer the
question.

> q2) How would this vary if salt were added in the amounts of the gulf
> of mexico?

You need to look up the density of sea water and compare that to fresh
water. You can then determine the feet per atmosphere of pressure for
sea water, and that should give you enough info to answer the question.

$.02 -Ron Shepard

From: Uno on 5 Jun 2010 22:25

On 6/5/2010 4:10 AM, robin wrote:

> BTW, without the kind, this is a single-precision constant.

Thx, robin, default precision is fine for starters. I want to make this
as legible as possible. We're all familiar with kind values, but they
might be a stumbling block to people who haven't seen fortran for a
decade or two.

E:\gcc_eq32>gfortran -Wall -Wextra p1.f90 -o out.exe

E:\gcc_eq32>out
atmos is 160.93440

E:\gcc_eq32>type p1.f90
implicit none

real :: feet_per_mile, atm_per_mile, atmos

feet_per_mile = 5280
atm_per_mile = 32.808399169

atmos = feet_per_mile / atm_per_mile

print *, "atmos is ", atmos

endprogram
! gfortran -Wall -Wextra p1.f90 -o out.exe

E:\gcc_eq32>

I have no idea why this didn't work last night.
--
Uno

From: Uno on 5 Jun 2010 22:56

On 6/5/2010 10:26 AM, Ron Shepard wrote:
> In article<86ulj7Ff3dU1(a)mid.individual.net>, Uno<merrilljensen(a)q.com>

> You cannot know. If the pressure within the pipe is greater than the
> pressure at 32.8 ft, then the liquid will continue to flow, but at a
> slower rate. If the pressure within the pipe is less than the pressure
> at 32.8 ft, then it will flow in the opposite direction.
>
> So you need an additional important piece of information to answer the
> question.

Right.

Let's say the pressure is typical city water pressure. This isn't too
hard for anyone to measure.

E:\gcc_eq32>gfortran -Wall -Wextra p1.f90 -o out.exe

E:\gcc_eq32>out
atmos is 160.93440
city_pressure is 65.000000
atmos2 is 4.5699549
depth is 149.93291

E:\gcc_eq32>type p1.f90
implicit none

real :: feet_per_mile, feet_per_atmos, atmos
real :: city_pressure, atmos_per_pound, atmos2
real :: depth

! values
feet_per_mile = 5280
feet_per_atmos = 32.808399169
city_pressure = 65 !typical water pressure in lb/in^2
! http://en.wikipedia.org/wiki/Atmosphere_(unit)
atmos_per_pound = 70.307E-3

! calculations
atmos = feet_per_mile / feet_per_atmos
atmos2 = city_pressure * atmos_per_pound
depth = feet_per_atmos*atmos2

!output
print *, "atmos is ", atmos
print *, "city_pressure is ", city_pressure
print *, "atmos2 is ", atmos2
print *, "depth is ", depth
endprogram
! gfortran -Wall -Wextra p1.f90 -o out.exe

E:\gcc_eq32>

So, if instead of opening a water spigot at seal level, you went 150
feet down, would it have no net flux?

>
>> q2) How would this vary if salt were added in the amounts of the gulf
>> of mexico?
>
> You need to look up the density of sea water and compare that to fresh
> water. You can then determine the feet per atmosphere of pressure for
> sea water, and that should give you enough info to answer the question.

Ok.

Gotta run
--
Uno

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